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Suggest a calculatorOne-Rep Max Estimator
Enter the weight you lifted and how many reps you completed.
How this works
Each formula estimates your one-rep max (1RM) from a lighter, multi-rep set, but they were derived from different research datasets, so they don't agree perfectly — averaging all four (as the result above does) is more robust than trusting any single one.
- Epley: 1RM = weight × (1 + reps ÷ 30) — simple and widely used, but tends to run high at higher rep counts.
- Brzycki: 1RM = weight × 36 ÷ (37 − reps) — assumes a near-linear fatigue curve; the formula breaks down at 37 reps (division by zero), so it's left out above 36.
- Lombardi: 1RM = weight × reps^0.10 — a power-law curve that estimates more conservatively than Epley or Brzycki.
- Mayhew et al.: 1RM = 100 × weight ÷ (52.2 + 41.9 × e^(−0.055 × reps)) — from a regression on bench-press data, flattening out at high rep counts.
All four are estimates, not measurements — actual 1RM depends on technique, fatigue, and the specific lift, and accuracy drops noticeably above about 10–12 reps.
Percentage-Based Training Table
Enter your one-rep max to see suggested weights at common training percentages.
Strength Score (Wilks)
Compare relative strength across bodyweights using the Wilks formula.
Plate Loading Calculator
Enter the target weight and bar weight to see plates needed per side.
5/3/1 Training Planner
Enter a recent weight/rep set for each lift to estimate your one-rep max, then generate a training-max-based plan (Jim Wendler's 5/3/1).
Compound Interest Calculator
See how a lump sum grows over time when interest compounds on itself.
How this works
Future value is calculated with the standard compound interest formula: A = P × (1 + r/n)^(n×t), where P is your principal, r is the annual interest rate as a decimal, n is how many times per year interest compounds, and t is the number of years.
Compounding more frequently (monthly instead of annually, say) produces a slightly higher return for the same nominal rate, because each period's interest starts earning its own interest sooner. This calculator models a single lump-sum deposit only — it doesn't add any regular contributions on top; for that, use the Investment/DCA Growth calculator instead.
Recipe Scaling Calculator
Scale every ingredient in a recipe up or down to a new serving size.
Cooking Measurement Converter
Convert cups/tablespoons/teaspoons to grams (or back) for a specific baking ingredient. Values are approximate reference figures — actual weight varies with how an ingredient is packed or sifted.
GPA Calculator
Compute your grade point average from a list of courses, grades, and credit hours (standard US 4.0 scale).
Investment / DCA Growth Calculator
Project how an initial lump sum plus regular contributions grows at an expected annual return.
Baker's Percentage Calculator
Convert a recipe between ingredient weights and baker's percentages (each ingredient as a % of total flour weight).
How this works
Baker's percentage expresses every ingredient's weight as a percentage of the total flour weight, which is always defined as 100% — even when a recipe blends multiple flours, their combined weight is the 100% baseline. Converting weights to percentages, or percentages back to weights, is a straightforward proportion: percentage = ingredient weight ÷ total flour weight × 100.
Because everything scales off flour rather than total dough weight, baker's percentages make it easy to scale a recipe up or down, or compare hydration and other ratios across recipes of completely different sizes, without recalculating each ingredient by hand.
Loan / Mortgage Amortization Calculator
Compute the fixed monthly payment and full amortization schedule for a loan or mortgage, with an optional overpayment.
Cooking Time Conversion Calculator
Estimate how cooking time should change when you resize the pan/dish or scale the batch quantity. These are rule-of-thumb estimates — always check for doneness near the estimated time.
Calories Per Serving Calculator
Add the calories contributed by each ingredient and the number of servings the recipe makes.
Credit Card Interest & Payoff Calculator
See how long it takes to pay off a credit card balance and how much interest it costs, with a fixed payment or a shrinking minimum payment.
Debt Payoff Planner
Compare the "snowball" (smallest balance first) and "avalanche" (highest interest rate first) strategies for paying off several debts with a fixed total monthly budget.
Freelance/Hourly Rate Calculator
Work out the hourly rate you need to charge to hit a target income, accounting for business expenses and realistic billable hours.
Savings Goal Calculator
Find out how much you need to save each month to reach a target amount by a target date.
Emergency Fund Calculator
Recommends how large your emergency fund should be, based on essential monthly expenses and how many months of coverage you want.
Inflation Impact Calculator
See how inflation erodes purchasing power over time — both directions use the same underlying math.
Driving Distance & Time Calculator
Estimate driving time and total trip time from distance, average speed, and any planned stops.
Oven Temperature Converter
Convert between Celsius, Fahrenheit, and UK Gas Mark. Fan/convection ovens typically run about 20°C (1 gas mark) cooler than these conventional-oven figures.
Meat Doneness Guide
Shows the target internal temperature and pull temperature (before carryover cooking during rest) for your chosen doneness.
Coffee Brew Ratio Calculator
Calculate coffee dose or water/yield from a dose:water ratio, with sensible defaults per brew method.
Time Zone Converter
Convert a time of day between two fixed UTC offsets (entered manually, since there's no live time-zone database here).
Dough Hydration Calculator
Typical bread doughs range roughly 60-100% hydration.
Salary After Tax Calculator
Define your own progressive tax brackets and social security rate — the defaults below are illustrative, not any specific country's tax code.
Salary Converter
Convert a pay rate between hourly, monthly, and annual figures.
Rent vs Buy Calculator
Compares the net cost of renting vs. buying over your chosen horizon — lower net cost wins.
Net Worth Growth Projection Calculator
Projects how net worth (assets minus liabilities) grows over time from steady monthly savings and expected investment growth.
Fuel Cost Calculator
Calculate how much a trip will cost in fuel, in metric or imperial units.
Fuel Economy Converter
Convert a fuel economy figure between US MPG, UK MPG, L/100km, and km/L.
Retirement Savings Calculator
Projects your savings at retirement age and counts down the years and days remaining.
Jet Lag Recovery Calculator
A rough rule-of-thumb estimate — eastward travel is generally harder to recover from than westward travel for the same number of zones.
EV Charging Cost Calculator
Estimate the cost to fully charge an EV, its full-charge range, and the cost of a specific trip.
FIRE Calculator
Estimates how many years until your invested savings can sustainably cover your living expenses, per the 4% rule.
Petrol vs Diesel Break-Even Calculator
Find the distance or time it takes for a diesel car's lower running costs to offset its higher upfront price.
Rule of 72 Calculator
Estimate how many years it takes an investment to double at a fixed annual rate, using the Rule of 72 and more precise variants for comparison.
EV vs Petrol Total Cost of Ownership Calculator
Compare the total cost of ownership of an EV versus a petrol car over a chosen period, combining net purchase cost, energy/fuel cost, and maintenance.
Electric vehicle
Petrol car
Car Depreciation Calculator
Project a car's resale value over time using either a declining-balance (% per year) or straight-line (residual value over useful life) depreciation model.
Trip Budget Calculator
Add up per-day costs across the whole trip plus one-off fixed costs, to get a total projected trip cost and average cost per day.
Car Loan/Lease Payment Calculator
Calculate the fixed monthly payment for financing a car, either as a standard amortizing loan or as a two-part lease (depreciation fee plus finance fee).
Engine Power & Torque Converter
Convert engine power between horsepower and kilowatts, torque between newton-meters and pound-feet, and optionally pair a torque value with an RPM to see the corresponding power. Fill in power, torque, or both.
0-100 km/h Acceleration Estimator
Rough estimate of acceleration time using a simplified kinetic-energy model. This is a ballpark figure, not a precise prediction — real acceleration also depends heavily on gearing, traction, and the engine's torque curve.
Stopping Distance Calculator
Estimates total stopping distance as reaction distance (traveled before braking starts) plus braking distance, based on speed and road surface.
How this works
Total stopping distance is the sum of two separate phases: reaction distance (speed × reaction time, since the car keeps moving at a constant speed while the driver perceives and reacts to a hazard) plus braking distance (speed² ÷ (2 × deceleration), from the constant-deceleration kinematics of coming to a stop).
Braking distance grows with the square of speed, not linearly — doubling your speed quadruples the distance needed to stop, all else being equal. The deceleration values used for dry (7.5 m/s²), wet (5 m/s²), and icy (2 m/s²) surfaces are rough, commonly-cited averages for typical passenger-car braking, not a substitute for a specific vehicle's actual tested performance.
Gear Ratio / RPM Calculator
Calculate vehicle speed from engine RPM, or the RPM needed for a target speed, given the gearbox ratio, final drive ratio, and tyre diameter.
Tire Size & Speedometer Error
Decode a tyre size code (e.g. 225/45R17 = width 225mm, aspect ratio 45%, rim diameter 17in) into overall diameter and circumference, compare it against a different tyre size, and see the resulting speedometer error.
Original tyre
New tyre
Currency Converter
Convert an amount between currencies using an exchange rate you type in yourself (no live rates). Use the swap toggle to convert back the other way with the inverse of the same rate.
Wheel Offset & Clearance (ET)
Estimate how changing a wheel's width and/or offset (ET) shifts it outward toward the fender or inward toward the suspension/strut. This is a rough approximation only — it doesn't account for suspension travel, steering lock, or fender rolling, and is not a fitment guarantee.
Old wheel
New wheel
Available clearance (optional, measured yourself)
Roof Box Fuel Penalty
Estimate the extra fuel and cost a roof box adds to a trip from a consumption penalty percentage you enter. Real-world figures are roughly 10-20% at motorway speeds (~100km/h), rising to 25-35% for large boxes at higher speeds.
Percentage Calculator
Find X% of Y, work out what percent one number is of another, calculate the percentage increase or decrease between two values, or work backwards from a final value and percent change to find the original value.
Tip Calculator / Bill Splitter
Work out the tip on a bill and split the total evenly across a group.
Sales Tax / VAT Calculator
Add sales tax/VAT to a pre-tax price, or work backwards from a tax-inclusive price to find the pre-tax amount and the tax portion.
Fraction Calculator
Add, subtract, multiply, or divide two fractions. The result is simplified to lowest terms, with a mixed-number form and decimal equivalent.
Ratio & Proportion Calculator
Simplify a ratio A:B to lowest terms, or solve a proportion A:B = C:D for whichever single value you leave blank.
Fill in exactly three of the four values below and leave the unknown one blank.
Luggage Weight Checker
Enter your airline's weight allowance(s) and list your packed items to see if each bag is within limit.
Average / Weighted Average Calculator
Find the simple arithmetic mean of a list of numbers, or a weighted average where each value counts more or less depending on its weight.
Age Calculator
Calculates exact age in years, months, and days from a birth date, plus total days and weeks lived.
Sunrise/Sunset & Daylight Calculator
Estimates sunrise, sunset, and total daylight duration for a date and location using a standard solar-position approximation (accurate to within a minute or two). Enter the location's UTC offset manually — there's no live time-zone database here.
How this works
This uses the same closed-form solar-position approximation behind NOAA's solar calculator (the "sunrise equation"): from the day of the year it derives the sun's declination and the equation of time, combines those with your latitude to find the hour angle at which the sun crosses the horizon, then converts that to sunrise and sunset clock times for your longitude and UTC offset. It calculates for solar noon rather than tracking the sun continuously through the day, which keeps the math simple while staying accurate to within a couple of minutes for most latitudes.
Near the poles the sun can stay above the horizon all day (polar day) or below it entirely (polar night) for parts of the year — the calculator detects both cases and reports them explicitly rather than showing a nonsensical time.
Moon Phase Calculator
Estimates the moon's phase and illumination for a given date, using a simplified synodic-month approximation (accurate to roughly a day, not ephemeris precision).
How this works
The moon completes one full cycle of phases — a synodic month — in about 29.53 days on average. This calculator counts how many days have elapsed since a known reference new moon (2000-01-06), takes the remainder after dividing by that synodic month length, and uses the resulting fraction of the cycle to name the current phase and estimate illumination as a smooth cosine curve (0% at new moon, 100% at full moon).
Because the real lunar orbit is slightly elliptical — the moon speeds up and slows down over the course of a month — this simplified method is accurate to roughly a day, not the ephemeris-level precision of a full astronomical calculation.
Warm-Up Set Calculator
Generates a ramping warm-up progression leading up to your working weight, so you arrive properly primed without wasting energy.
Date Difference / Countdown
Computes the time between two dates — or a countdown to a future date — in days, weeks, and years/months/days. Works either way round.
DOTS Score
Compare powerlifting totals across bodyweights and sexes using the IPF-adopted DOTS formula (the modern successor to Wilks).
Date Plus/Minus Days
Finds the calendar date a number of days before or after a starting date, plus its day of the week.
Voltage & Plug Type Checker
Static reference lookup (not a live database) of mains voltage, frequency, and plug type by country, with an adapter/converter recommendation for traveling between two of them.
Electrical Load / Ohm's Law Calculator
Solve for voltage, current, resistance, or power using Ohm's Law (V = I × R) and Watt's Law (P = V × I) — e.g. enter voltage and wattage to find the amperage a circuit breaker needs to handle.
Working Days Calculator
Counts business days (Monday-Friday) between two dates, inclusive of both endpoints, or adds/subtracts a number of business days to a single date — optionally excluding a list of holiday dates.
Time Duration Calculator
Add or subtract two H:MM:SS durations, or compute the elapsed time between two times of day (24-hour, supports overnight shifts).
IPF GL Points
Computes the IPF's official Goodlift (GL) Points score, used to rank lifters across bodyweights, sexes, and raw/equipped divisions in competition.
Unit Converter
Converts between units of length, area, volume, weight, temperature, and speed.
FFMI Calculator
Computes Fat-Free Mass Index (FFMI), a height-normalized measure of muscularity, from weight, height, and body fat percentage.
BMI Calculator
Computes Body Mass Index (BMI) from weight and height, and classifies it against the standard WHO bands.
How this works
Body Mass Index is weight in kilograms divided by height in meters squared (BMI = kg ÷ m²) — weight and height are converted to those units first regardless of which units you entered them in. The result is compared against the standard World Health Organization adult bands: under 18.5 is classified underweight, 18.5–24.9 normal weight, 25–29.9 overweight, and 30 or above obese.
BMI doesn't account for muscle mass, bone density, age, or sex, so it can misclassify very muscular or very lean people — it's a population-level screening tool, not a diagnosis of individual body composition.
Lean Body Mass Calculator
Estimates lean body mass (everything in the body that isn't fat) either from a known body fat percentage, or from height/weight/sex alone using the Boer formula.
Body-Fat Percentage Estimator
Estimates body fat percentage from tape-measure circumferences using the US Navy method (Hodgdon & Beckett, 1984) — no calipers required. Typical accuracy is ±3-4%.
TDEE Calculator
Estimates Total Daily Energy Expenditure (calories burned per day) using the Mifflin-St Jeor BMR equation scaled by an activity-level multiplier.
Macro Calculator
Converts a daily calorie target and a protein/carb/fat percentage split (must sum to 100%) into gram targets for each macronutrient.
Weight-Loss Timeline
Estimates how long it will take to reach a goal weight given a daily calorie deficit, using the standard approximation that 1 kg of body fat ≈ 7700 kcal (1 lb ≈ 3500 kcal).
Bulking Calorie Calculator
Computes a recommended daily calorie target for lean muscle gain, starting from your TDEE (see the TDEE calculator) and applying a moderate surplus sized to limit excess fat gain.
Running Pace Calculator
Converts between running pace, total time, and distance — enter the two you know and solve for the third.
Paint Calculator
Estimates how much paint you need for a room, based on wall area, door/window deductions, number of coats, and the paint's coverage rate.
Wallpaper Calculator
Calculates how many rolls of wallpaper you need, accounting for the roll's dimensions, pattern repeat (which trims each strip to keep the pattern aligned), and a waste allowance.
Flooring Calculator
Calculates how much flooring material (laminate, hardwood, vinyl plank, carpet, etc.) and how many boxes you need for a room, including a waste allowance for cuts and layout. Add more than one section for an L-shaped room, an alcove, or a connecting hallway.
Race Time Predictor
Predicts your finish time at a target race distance from a known/recent result at a different distance, using the Riegel endurance-performance model.
Tile Calculator
Calculates how many tiles you need for a floor or wall, accounting for the grout line width (which effectively enlarges each tile's footprint) and a waste allowance.
Concrete Calculator
Calculates the concrete volume needed for a slab, footing, or column, and converts it into a number of pre-mixed bags.
How this works
Volume comes from the shape you're pouring — length × width × thickness for a rectangular slab, footing, or column, or π × (diameter ÷ 2)² × height for a cylindrical pour like a post hole — all in meters, giving cubic meters. A waste percentage is added on top (spillage, uneven subgrade, and over-excavation routinely eat 5–10% extra), and the padded volume is divided by a bag's stated yield and rounded up, since you can't buy a fraction of a bag.
For larger pours, the calculator also compares that bagged-concrete cost against a ready-mix delivery quote, since ready-mix usually beats bags on both cost and labor once you're pouring more than roughly a cubic meter or two.
Heart-Rate Training Zone Calculator
Computes personalized heart-rate training zones using the Karvonen method (Heart Rate Reserve), which accounts for your resting heart rate rather than just age.
Sleep Cycle Calculator
Suggests bedtimes or wake-up times aligned to complete ~90-minute sleep cycles, so you're more likely to wake between cycles rather than mid-deep-sleep. A general guideline based on population averages, not a substitute for a sleep study — individual cycle length varies (roughly 70–120 minutes).
VO2max Estimator
Estimates VO2max (maximal aerobic capacity) from the distance covered in a 12-minute Cooper run test — no lab equipment required.
Daily Water Intake Calculator
Estimates how much water to drink per day based on body weight, with adjustments for activity level and climate. A general wellness estimate, not medical advice.
Caffeine Half-Life Calculator
Shows how much caffeine is still active in your body after a coffee, tea, or energy drink, using exponential decay. A simplified population-average model for general awareness — not a medical tool.
Gravel Calculator
Calculates how much gravel you need, by volume and by weight (since gravel is usually sold/delivered by the ton), to cover an area to a given depth.
Blood Alcohol Content (BAC) Calculator
This is a rough population-average estimate for entertainment/educational purposes only. It is NOT accurate enough to judge fitness to drive or to make any legal, medical, or safety decision — individual results vary hugely with food intake, medication, metabolism, and drinking rate. Never drive after drinking.
Cycling FTP Calculator
Estimates Functional Threshold Power (FTP) from a 20-minute maximal test and derives Coggan's 7 power training zones.
Mulch/Soil Calculator
Calculates how much mulch or garden soil you need to cover a bed to a target depth. Typical mulch depth is 5–10 cm; a new raised bed typically wants 15–20 cm of soil.
Roof Area Calculator
Converts a roof's flat footprint area (building outline as seen from above) into its actual sloped surface area, since roofing material needs to cover the slope, not the footprint.
Roof Pitch Calculator
Converts a measured rise and run into the slope ratio, "X-in-12" notation, and angle in degrees — whichever format a supplier, code table, or contractor expects.
Climbing Grade Converter
Converts climbing grades between the V-scale (US bouldering), Font (European bouldering), and YDS (US route climbing) systems. YDS is a different type of scale from V-scale/Font, so it can only convert to/from itself.
Ladder Angle/Safety Calculator
Calculates the safe base-to-wall distance (the 4:1 rule, ≈75.5°) and minimum ladder length for a given support height. General safety guidance — not a substitute for the ladder manufacturer's instructions or a professional site-specific assessment.
UV Exposure / Sun Safety Calculator
Estimates how many minutes you can stay in the sun before you're likely to start burning, based on the current UV index and your Fitzpatrick skin type. A rough population-average estimate for general awareness, not a substitute for real-world sun safety judgment.
Pet Age Calculator
Converts a dog's or cat's age into human-equivalent years, using modern research-based formulas rather than the old (inaccurate) "multiply by 7" myth. A population-average research-based estimate, not a substitute for a vet's assessment of an individual animal.
Pregnancy Due Date Calculator
Estimates a due date from the last menstrual period (Naegele's rule) or a known conception date. A statistical estimate - only about 5% of babies arrive exactly on their due date - not a substitute for ultrasound dating or a healthcare provider's guidance.
Earth Rotation & Orbit Distance Calculator
See how far you've actually traveled through space just by standing still, from Earth's rotation on its axis and its orbit around the Sun. A simplified educational model, not a precision astronomical calculation.
Decking Calculator
Estimates how many deck boards and screws you'll need, based on deck size, board dimensions, the gap left between boards for drainage/expansion, and joist spacing. A planning estimate - always round up material orders and check local building requirements.
Staircase Calculator
Works out how many steps a staircase needs for a given floor-to-floor height and available run, then checks the resulting rise and run against common comfort/code-recommended ranges. Local building codes vary — use this as general guidance, not a substitute for checking the code that applies to your project.
Fence Calculator
Estimate how many posts, panels, or rails a straight fence run needs, and how they space out - helpful for planning material purchases and marking post-hole locations before digging.
Heating Cost Calculator
Estimates seasonal or monthly heating cost using the degree-day method, from home size, insulation quality, local heating degree-days, and energy price. A simplified estimate, not a substitute for a full home energy audit.
HDD sums, over the heating season, max(0, base temperature − average daily outdoor temperature) — typically against an 18°C base. Higher HDD means a colder season. Check your local weather service or utility for this figure; there's no live lookup here.
~0.85–0.95 for a modern condensing gas boiler; ~2.5–4.0 as a COP for a heat pump.
Unix Timestamp Converter
Convert a Unix timestamp into a human-readable date, or a date/time back into a timestamp. The epoch is 1970-01-01T00:00:00Z, counted in seconds or milliseconds and not adjusted for leap seconds.
Password Strength / Entropy Calculator
Estimates entropy from the length and character classes actually used in a password, then estimates brute-force crack time at a few common guessing rates. This measures resistance to random guessing, not to dictionary or pattern-based attacks.
Color Format Converter
Convert a color between HEX, RGB, and HSL.
Number Base Converter
Convert a value between binary, octal, decimal, and hexadecimal.
Base64 Encoder/Decoder
Converts plain text to Base64 and back - useful for inspecting Basic Auth headers, data URIs, or encoded tokens. UTF-8 text is fully supported. Choose URL-safe below to encode using -/_ with padding stripped, instead of the standard +///= alphabet. Decoding accepts both alphabets regardless of this setting; whitespace/newlines in the input are stripped automatically.
Regex Tester
Test a JavaScript regular expression against sample text: see every match highlighted inline, plus each match's capture groups. Matches are always found and listed in full regardless of the "g" flag below, since that's inherent to this tool's match-list/highlight view - the "g" checkbox mirrors the semantics you intend for your own use of the pattern elsewhere.
Horizon Distance Calculator
Calculate how far away the visible horizon is based on your height above the surface, accounting for Earth's curvature and (optionally) atmospheric refraction. Refraction depends on weather/temperature gradients, so the refracted figure is a typical-conditions estimate, not exact.
Barometric/Altitude Air Pressure Calculator
Estimates atmospheric pressure and water's boiling point at a given altitude, using the standard barometric formula. Only valid within the troposphere (below ~11 km).
Solar Panel Sizing & ROI Calculator
Estimates how many solar panels you need to cover a target daily energy use, and how long the system takes to pay for itself. Sun-hours and energy price are manual inputs - no live pricing or irradiance data is fetched.
Projectile Motion & Fall Time Calculator
Calculates time of flight, maximum height, and range for a launched projectile - or the fall time for a simple drop when speed/angle are zero. Ignores air resistance and assumes flat, level ground and constant gravity.
URL Encoder/Decoder
Percent-encodes or decodes text for safe use in URLs (RFC 3986). Space becomes %20, not + - the +-for-space convention belongs to form bodies, not this tool. Encoding already-encoded text will double-encode it (a literal % becomes %2520).
JWT Decoder
Decodes a JSON Web Token's header and payload so you can inspect its claims. This tool only decodes - it does not verify the signature.
UUID Generator
Generate RFC 9562 UUIDs for use as primary keys, request IDs, correlation IDs, etc. Everything runs locally in your browser using the Web Crypto API - nothing is sent anywhere.
JSON Formatter, Minifier & YAML Converter
Pretty-print or minify JSON, check that it's valid, or convert between JSON and YAML. The YAML support is a hand-written parser covering a common subset (block mappings/sequences, quoted and bare scalars, comments) — not the full spec: anchors, flow style ({a: 1} / [1, 2]), multi-line block scalars (| / >), tag directives, and tab indentation are all rejected with an error rather than silently mis-parsed.
Cron Expression Generator & Translator
Build a standard 5-field (Vixie/POSIX-style) cron expression from plain fields, or paste one in — including @yearly-style macros — to get a plain-English description of when it runs.
CIDR/Subnet Calculator
Enter an IPv4 address and CIDR prefix length as a single a.b.c.d/p value (e.g. 192.168.1.10/26) to get the network and broadcast addresses, subnet mask, wildcard mask, usable host range, and host counts.
How this works
A CIDR prefix like /26 defines a subnet mask — the count of leading 1 bits — that splits an IPv4 address into a fixed network portion and a variable host portion. Applying that mask to your address with a bitwise AND gives the network address; flipping the mask and OR-ing it in gives the broadcast address (the highest address in the range). Everything in between is usable for hosts.
That's why a /24 gives 254 usable hosts (2⁸ − 2, for its 8 host bits) rather than the full 256: the all-zeros host address identifies the network itself, and the all-ones address is reserved for broadcast. The two exceptions are /31 (point-to-point links, where both addresses are usable per RFC 3021) and /32 (a single host, with no separate network or broadcast address at all).
IPv4 to IPv6 Converter
Converts between an IPv4 address and its IPv4-mapped IPv6 form (RFC 4291 §2.5.5.2, ::ffff:a.b.c.d) - the form used when an IPv6-only stack represents an IPv4 address. The deprecated IPv4-compatible form (::a.b.c.d, no ffff) is also supported.
Wind Chill & Heat Index Calculator
Estimate the "feels like" temperature for cold, windy conditions (wind chill) or hot, humid conditions (heat index), using the official U.S. National Weather Service (NWS/NOAA) formulas. Both are approximations with their own margin of error.
Hash Generator
Computes a hex digest of text or a local file for checksums, integrity checks, or comparing values without exposing the original content. Everything runs locally in your browser - nothing is sent anywhere, including the contents of a selected file. MD5 and SHA-1 are cryptographically broken and deprecated for security purposes (e.g. password storage, digital signatures) - use them here only for checksums or legacy compatibility, and prefer SHA-256 or SHA-512 otherwise.
Unix Permissions (chmod) Calculator
Converts Unix file permissions between symbolic form (rwxr-xr-x) and octal/numeric form (755). A pasted full ls -l string (e.g. drwxr-xr-x) has its leading file-type character stripped automatically. Setuid/setgid/sticky bits are supported as an optional 4th leading octal digit (e.g. 4755), or folded into the symbolic string's execute slots (s/S for owner/group, t/T for other). A 1- or 2-digit octal mode is treated as left-padded with zeros (e.g. 5 is read as 005).
CSS Unit Converter
Converts a CSS length between px, rem, vw, vh, and pt at once, using the root font-size and viewport dimensions you supply — no assumptions are made about this page's own viewport or font-size.
Docker/Kubernetes Resource Calculator
Suggests sensible CPU and memory requests/limits for a container from observed usage, instead of guessing round numbers. The request (used for scheduling and as a guaranteed floor) is set to average usage; the limit is set to peak usage plus a headroom factor.
SQL Formatter
Reformat a raw SQL query into consistently indented, consistently cased SQL, or minify it to one line. This is a hand-written tokenizer covering common ANSI-ish SQL — not a full multi-dialect parser. Keywords inside string/quoted-identifier literals are left untouched, and subqueries in parentheses are preserved as-is rather than recursively re-indented.
SVG to PNG/JPEG Converter
Converts an SVG image to a PNG or JPEG file entirely in your browser - nothing is uploaded anywhere. JPEG has no transparency, so a background color is used to flatten any transparent areas first.
Image Compressor
Re-encodes an image as JPEG or WebP at a chosen quality to reduce its file size, entirely in your browser. PNG isn't offered as an output here since PNG is lossless - no quality setting can shrink it; use the Image Format Converter if you specifically need a PNG.
Image Resizer
Resizes an image to a target pixel size or a percentage scale, entirely in your browser, keeping the source file's format. Upscaling beyond the original resolution just stretches existing pixels - there's no way to add detail that wasn't there.
Image Format Converter
Converts an image between PNG, JPEG, and WebP entirely in your browser. JPEG has no transparency, so a background color is used to flatten any transparent areas first; PNG and WebP output keep transparency as-is.
Base64 <-> Image Converter
Converts an image file to a base64 data URI - for inlining in CSS (background-image: url(data:...)) or HTML - or decodes a data URI or raw base64 string back into a downloadable image. Everything runs locally in your browser; nothing is uploaded anywhere.