Unit Converters
Fast, exact unit conversion across length, mass, temperature, volume, area, speed, pressure, energy, cooking and digital storage.
47 tools, all running in your browser.
Fig 1 A factor is a fixed offset
Move to read · ← → · Space: units
The slide is offset by the logarithm of the factor, so every number on the slide sits over its converted value. The converters here do the same multiplication, in your browser.
Most used
Aspect Ratio Calculator Solve any missing width or height for a ratio, simplify W:H with the GCD, read the megapixels and preview the shape. Presets for 16:9, 4:5 and 9:16. Celsius to Fahrenheit Celsius to Fahrenheit with the formula shown using your number, a drag-through slider, a Kelvin column and a table of reference points. CM to Inches Convert cm to inches with exact 2.54 arithmetic, tape-measure fractions down to 1/16, a feet-and-inches readout and column batch mode. KG to LBS Kilograms to pounds using the exact 0.45359237 definition, with stone-and-pounds and pounds-and-ounces readouts and column batch mode. Length Converter Convert cm to inches, metres to feet, km to miles and 13 other length units instantly. Exact factors, formula shown, works offline. Temperature Converter Convert Celsius to Fahrenheit, Kelvin, Rankine and Réaumur with the offset maths shown, an absolute-zero guard and a full lookup chart. Weight Converter Convert kg to lbs, grams to ounces, stone to kilos and tonnes to tons with exact factors, a two-way field and a full reference table.
Everything else
Angle Converter Convert degrees to radians, gradians, arcminutes, arcseconds, turns, milliradians and NATO mils, with exact π-based factors. Area Converter Convert square metres to square feet, acres to hectares, and every other area unit, with land-measure factors that are exact by definition. Celsius to Kelvin Celsius to Kelvin with the exact 273.15 offset, absolute zero marked, Fahrenheit alongside and a slider from absolute zero to 1000 °C. Clothing Size Converter Convert women's and men's clothing sizes and jeans waists across US, UK, EU, French, Italian and Japanese labels, driven by body measurements. Cooking Converter Convert cups to grams, tablespoons to millilitres and ounces to cups using real per-ingredient densities for flour, sugar, butter and more. Cups to Grams Cups to grams by ingredient, with fraction input (1 1/2, 3/4), four cup standards, ounces alongside and a full chart for the ingredient you pick. Data Storage Converter Convert bytes, KB, MB, GB, TB and PB with a switch between 1000-based and 1024-based counting, plus the IEC KiB, MiB and GiB units. Energy Converter Convert joules, kilojoules, calories, kcal, watt-hours, kWh, BTU, therms and electronvolts with exact definitions and a live formula. Fahrenheit to Celsius Fahrenheit to Celsius with the subtraction shown in full, a slider covering weather through oven range, and Kelvin alongside. Feet to Meters Feet to metres with feet-and-inches input: type 5'10" or 5 ft 10 in and get metres, centimetres and millimetres at once. Fever Temperature Converter Convert a thermometer reading between Celsius and Fahrenheit and see which band it falls in, from hypothermia to high fever, with the thresholds listed. Fuel Economy Converter Convert mpg to L/100km, US mpg to UK mpg and km/L, with the reciprocal relationship handled correctly instead of a naive multiply. Grams to Cups Grams to cups for over 100 ingredients — flour, sugar, butter, rice, cocoa — with a cup-standard selector and honest density notes. Grams to Ounces Grams to avoirdupois ounces with pounds-and-ounces output for postage, plus a kitchen reference table including the awkward values. Inches to CM Turn inches into centimetres exactly. Understands 5 1/2, 5½ and 5'6" entries, gives mm and metres too, and converts a pasted column in one go. Inches to MM Convert fractional or decimal inches to millimetres exactly — 3/8, 1 1/4 and 0.375 all work — with a full sixteenths-to-mm reference table. KG to Pounds and Ounces Kilograms to pounds and ounces — the format used for birth weights and parcels — with total ounces and grams shown alongside. KG to Stone Kilograms to stone with a proper stone-and-pounds answer — 75 kg is 11 st 11.3 lb — plus decimal stone and pounds for forms. KM to Miles Kilometres to miles, exactly. Includes the true half-marathon and marathon distances, plus metres, feet and yards for every value. LBS to KG Pounds to kilograms with the exact 0.45359237 factor. Accepts stone-and-pound entries like 11 st 4 lb and converts pasted columns. Meters to Feet Metres to feet with a proper feet-and-inches answer, not just decimal feet: 1.75 m is 5 ft 8.9 in. Includes a height reference table. Miles to KM Miles to kilometres with exact 1.609344 arithmetic, race distances built into the table, and metres, yards and feet alongside. ML to Cups Millilitres to cups in all four standards at once — US customary, US legal, metric and imperial — plus fluid ounces, tablespoons and teaspoons. MM to Inches Millimetres to inches for the workshop: decimal inches plus the nearest 1/64, 1/32 and 1/16 fraction, and a printable mm-to-fraction chart. Ounces to Grams Ounces to grams with fraction input (1/2, 3/4, 1 1/2), plus kilograms, pounds and a pounds-and-ounces restatement of your entry. Oven Temperature Converter Convert oven temperatures between Celsius, Fahrenheit, gas mark and fan/convection, with the descriptive terms old cookbooks use and a full chart. OZ to Cups Answers both questions at once: ounces as volume (fluid ounces) and ounces as weight, side by side, because recipes use the word for both. Power Converter Convert kW to hp, PS to hp, watts, megawatts, BTU/h and tons of refrigeration — with all three horsepower definitions kept separate. Pressure Converter Convert bar to psi, kPa, MPa, atmospheres, torr, mmHg and inHg — for tyre pressures, blood pressure, weather and engineering work. Recipe Scaler Paste a whole ingredient list and rescale every quantity at once for a new serving count, re-rendered as clean fractions, with optional metric weights. Ring Size Converter Convert ring sizes between US, UK, EU/ISO and Japanese systems, plus an on-screen sizer you calibrate against a bank card and a printable strip. Screen Size Calculator Turn a screen diagonal into real width, height, viewing area and pixel density for any aspect ratio, with the Pythagoras working shown in full. Shoe Size Converter Convert shoe sizes between US, UK, EU and Japanese systems using foot length in centimetres — the only method that survives brand variation. Speed Converter Convert km/h to mph, m/s to km/h, knots, feet per second and Mach with exact factors and a printable two-way speed chart. Sticks of Butter Converter Convert sticks of butter to grams, ounces, cups and tablespoons. One US stick is exactly a quarter pound — 113.4 g, half a cup, 8 tablespoons. Stone to Pounds Stone to pounds and kilograms. Type 11 st 4 lb, 11.5 or just 11 — all three are understood, and a stone is always exactly 14 pounds. Tablespoons to Cups Tablespoons to cups with a tablespoon-standard selector — the US, metric and 20 mL Australian spoons differ — plus teaspoons, mL and grams. Time Converter Convert seconds, minutes, hours, days, weeks, months, years and nanoseconds, using the true 365.2425-day Gregorian year average. Volume Converter Convert litres, millilitres, US and imperial gallons, quarts, pints, cups and fluid ounces — with the US/UK difference handled properly. Yards to Meters Yards to metres for fabric, turf and sports fields — exact 0.9144 conversion with feet, inches and centimetres shown alongside.