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UNITS SECTOR · 22 TOOLS

Free Unit Converters Online

Length, weight, temperature, area, volume, speed and every other unit. 22 free tools, no sign-up.

Unit ConverterConvert length, weight, temperature, area, volume, speed, data and seven more kinds of units in one place.Unit ConvertersLength ConverterConvert mm, cm, inches, feet, metres, km, miles and 13 more length units at once — with the exact formula.Unit ConvertersWeight ConverterConvert kg, lbs, grams, ounces, stone, tonnes, carats, troy ounces and tolas — weight and mass in one place.Unit ConvertersTemperature ConverterConvert Celsius, Fahrenheit, Kelvin, Rankine and Réaumur instantly, with the formula and a reference chart.Unit ConvertersHeight ConverterConvert height between feet and inches, centimetres, metres and inches — live, both ways, with a height chart.Unit ConvertersVolume ConverterConvert litres, ml, US and UK gallons, pints, cups, fluid ounces, cubic feet and barrels — clearly labelled.Unit ConvertersData Storage ConverterConvert bits, bytes, KB, MB, GB, TB and binary KiB, MiB, GiB, TiB — and see why a 1 TB drive shows 931 GB.Unit ConvertersClothing Size ConverterConvert women’s, men’s, kids’, hat and bra sizes between US, UK, EU, India, FR, IT, AU, Japan and China.Unit ConvertersCooking ConverterConvert cups, tablespoons, teaspoons, ml and fl oz, plus cups ⇄ grams for flour, sugar, butter and more.Unit ConvertersTime ConverterConvert nanoseconds to millennia — seconds, minutes, hours, days, weeks, months and years in one view.Unit ConvertersShoe Size ConverterConvert men’s, women’s and kids’ shoe sizes (US, UK, EU, India, Japan) by foot length, with growing room.Unit ConvertersSpeed ConverterConvert km/h, mph, m/s, knots, ft/s, Mach and the speed of light — every speed unit at once, with formulas.Unit ConvertersWeather CalculatorWind chill, heat index, dew point, humidity, humidex and feels-like temperature, with risk levels, in °C or °F.Unit ConvertersFuel Economy ConverterConvert mpg (US and UK), L/100 km, km/L and gallons per 100 miles — reciprocal units handled correctly.Unit ConvertersArea ConverterConvert sq ft, m², acres and hectares, plus state-wise bigha, katha, guntha, cent, marla and kanal.Unit ConvertersEnergy ConverterConvert joules, kWh, kcal (food Calories), BTU, therms, eV and foot-pounds — exact factors, every unit at once.Unit ConvertersPower ConverterConvert watts, kW, MW, horsepower (hp, PS, electrical), BTU/h, tons of refrigeration and kcal/h instantly.Unit ConvertersPaper Size ConverterA, B, C, US, ANSI, ARCH, JIS and photo paper sizes in mm, inches, points and pixels at any DPI.Unit ConvertersAngle ConverterConvert degrees, radians, gradians, turns, arcminutes, arcseconds and mils — plus decimal degrees ⇄ DMS.Unit ConvertersRing Size Chart & ConverterConvert ring sizes between US, UK, India, EU and Japan, measure with a printable sizer or a calibrated on-screen circle.Unit ConvertersPressure ConverterConvert psi, bar, kPa, MPa, atm, kgf/cm², mmHg, inHg, torr and water columns — exact, with the formula.Unit ConvertersFrequency ConverterConvert hertz, kHz, MHz, GHz, rpm, bpm and rad/s — and see the period and wavelength of any frequency.Unit Converters

Quick conversions

Inches to CMCelsius to FahrenheitFeet to InchesCM to InchesFeet to CMFeet to MetersMeters to FeetCM to FeetLBS to KGInches to FeetKG to LBSFahrenheit to CelsiusGrams to PoundsMiles to KMPounds to GramsInches to MMKM to MilesMM to InchesMB to GBGB to MBGrams to OuncesOunces to GramsYards to MetersMPH to Km/hSquare Meters to Square FeetLiters to GallonsGallons to LitersKB to MBGB to TBSquare Feet to Square MetersKm/h to MPHOz to MLLiters to CupsCups to MLMeters to YardsML to OzML to CupsTB to GBL/100 km to MPGMPG to L/100 kmStone to KGkcal to kJkJ to kcalKG to StoneSquare Feet to AcresHP to kWkW to HPKnots to Km/hDecimal to Square FeetCent to Square FeetAcres to Square FeetCelsius to KelvinPSI to BarAcres to HectaresBar to PSIHectares to AcresAcre to CentBigha to AcreBigha to Square FeetGaj to Square FeetSquare Feet to GajFahrenheit to KelvinGuntha to Square FeetKelvin to CelsiusMarla to Square FeetGround to Square FeetGuntha to AcreKatha to Square FeetKanal to Square FeetBigha to KathaAcre to GunthaBiswa to Square FeetAnkanam to Square FeetKanal to MarlaAnkanam to Cent

Convert any measurement, metric or imperial

The world still measures in more than one system. India, Europe and most countries use metric units, the United States uses US customary units, and the UK mixes both, with miles on road signs, stone on the bathroom scale, litres at the petrol pump and pints at the pub. These free unit converters translate between them instantly, so a recipe in cups, a height in feet and inches or a speed limit in mph makes sense wherever you are.

Start with the all-in-one unit converter if you are not sure which category you need, or go straight to a dedicated tool for length, weight, temperature, area, volume, speed, data storage, pressure, energy or power. Everyday helpers cover cooking measurements, shoe sizes across US, UK, EU and Indian scales, and height in feet and centimetres.

The converters use the exact international definitions: one inch is exactly 2.54 cm and one pound is exactly 0.45359237 kg. Many show every related unit at once, so you can read off the one you need without converting twice. Results update in your browser as you type, which makes them quick to use on a phone in a shop, a kitchen, a workshop or a classroom. Cooks following an American recipe in Mumbai, nurses reading a weight in pounds and engineers working from a datasheet written in another system all rely on getting conversions exactly right.

Metric, imperial and US customary: what to watch for

Most conversion mistakes come from units that share a name but not a size:

  • Gallons and fluid ounces. A US gallon is 3.785 litres but a UK (imperial) gallon is 4.546 litres, and the fluid ounce differs too: 29.57 ml in the US and 28.41 ml in the UK.
  • Tons and tonnes. A metric tonne is 1,000 kg, a US short ton is 2,000 lb (about 907 kg) and a UK long ton is 2,240 lb (about 1,016 kg).
  • Cups. A US cup is about 237 ml, while the metric cup used in Australia and elsewhere is 250 ml. For flour and sugar, weighing in grams is far more reliable than measuring by volume.
  • Stone. UK body weight is often given in stone and pounds. One stone is 14 lb, or about 6.35 kg.

Quick conversions and everyday uses

Dedicated pages answer the most-searched pairs in one step, each with a reference table: cm to inches, kg to lbs, km to miles and Celsius to Fahrenheit, with more listed under Quick conversions on this page.

Home buyers in India can switch between square feet, acres and local land units such as bigha, guntha and marla with the area converter. Travellers can turn a US weather forecast into Celsius, and students can check physics homework in SI units. For calculations rather than conversions, such as the area of a room from its sides, use the math calculators.

Unit Converters: frequently asked questions

How many centimetres are in an inch?

Exactly 2.54. The inch has been defined as 25.4 mm by international agreement since 1959, so multiply inches by 2.54 to get centimetres and divide by 2.54 to go back.

How do I convert kg to pounds in my head?

Double the kilograms and add 10%. For 70 kg that gives 140 + 14 = 154 lb, very close to the exact 154.32 lb. The precise factor is 1 kg = 2.20462 lb.

Why does a 1 TB hard drive show only 931 GB?

Drives are sold in decimal units, where 1 TB is 10¹² bytes, but Windows reports binary units where one “GB” is 2³⁰ bytes. Nothing is missing, and the data storage converter shows both systems side by side.

What is the formula for Celsius to Fahrenheit?

Multiply by 9/5 (or 1.8) and add 32, so 30 °C is 30 × 1.8 + 32 = 86 °F. To go back, subtract 32 and multiply by 5/9.

Is a UK pint the same as a US pint?

No. A UK pint is about 568 ml and a US liquid pint about 473 ml, so a British pint is roughly 20% larger. The same ratio applies to quarts and gallons.

How do I convert feet and inches to centimetres?

Turn the height into inches first (feet × 12 + inches), then multiply by 2.54. For 5 ft 7 in that is 67 × 2.54 = 170.18 cm.