Unit Converter

Convert any measurement between unit systems instantly

Every day people need to translate measurements from one system to another. A recipe calls for fluid ounces but your measuring jug shows millilitres. A product's dimensions are listed in inches but you work in centimetres. The weather forecast on a foreign website shows Fahrenheit and you think in Celsius. A car's fuel efficiency is given in miles per gallon but you know litres per hundred kilometres. This unit converter handles all of these and more in one place.

Categories covered

Length: metres, centimetres, millimetres, kilometres, inches, feet, yards, miles, and nautical miles. Useful for construction, geography, sports, and everyday measurement.

Weight and mass: kilograms, grams, milligrams, tonnes, pounds, ounces, and US tons. Essential for cooking, shipping, fitness, and scientific work.

Temperature: Celsius, Fahrenheit, and Kelvin. The most commonly needed conversion across the world, since the US uses Fahrenheit while most other countries use Celsius.

Volume: litres, millilitres, cubic metres, cubic centimetres, US gallons, US fluid ounces, US cups, UK gallons, and UK fluid ounces. Vital for cooking, chemistry, and fuel measurement.

Area: square metres, square kilometres, square centimetres, square inches, square feet, square yards, square miles, and acres. Used in real estate, agriculture, and construction.

Speed: metres per second, kilometres per hour, miles per hour, knots, and feet per second. Relevant for travel, physics, and sports performance.

The metric and imperial divide

Most of the world uses the International System of Units (SI), colloquially called the metric system, because it is based on powers of ten and requires no memorisation of arbitrary conversion factors. The United States is one of only three countries (alongside Liberia and Myanmar) that has not officially adopted the metric system as its primary measurement system, which is why US-to-metric conversions remain so frequently needed.

The British imperial system sits between the two: the UK officially uses metric for most purposes but imperial units persist in everyday speech — people talk about their height in feet and inches, body weight in stone and pounds, road distances in miles, and beer in pints.

Temperature: the most requested conversion

Celsius to Fahrenheit is among the most searched unit conversions on the internet, and for good reason: temperatures are reported in different scales across different countries and understanding the difference is essential for travel, cooking, and interpreting weather forecasts. A quick reference: 0°C = 32°F (freezing), 20°C = 68°F (pleasant room temperature), 37°C = 98.6°F (normal body temperature), 100°C = 212°F (boiling water at sea level).

How the conversion works

Each category uses a base unit. For length, the base is the metre. All other units are defined by their exact relationship to the metre. Converting from any unit to any other unit goes through the base: value → base unit → target unit. For temperature, the special offset formula is applied directly.

All conversion factors used are the internationally agreed exact or highly precise definitions. The result is accurate to many significant figures, more than enough for any practical use.

How to use the converter

Choose a category — length, weight, temperature, volume, area or speed — then pick your source unit, type a value, and select the unit you want to convert to. The result appears immediately, and changing any of the three settings recalculates instantly, so comparing several units side by side takes only a few taps rather than several separate lookups.

Why the base-unit approach keeps every conversion accurate

Rather than storing a separate conversion factor for every possible pair of units, which would require hundreds of individual relationships and be a common source of small errors, this converter defines every unit in a category relative to a single base unit — the metre for length, the kilogram for weight, the litre for volume, and so on. Converting from any unit to any other therefore always happens in two clean steps: your input is converted to the base unit, and the base unit value is then converted to your target unit. This is exactly how professional measurement software and scientific calculators handle unit conversion internally, and it guarantees that a conversion between two obscure units is exactly as accurate as one between two common units, since both routes pass through the same well-defined base.

Cooking across measurement systems

Few situations make the metric-imperial divide more frustrating than following a recipe written in the other system. US recipes measure by volume — cups, tablespoons, fluid ounces — while much of the rest of the world measures by weight in grams, which is actually the more precise approach since a cup of tightly packed flour weighs noticeably more than a loosely spooned one. Converting a recipe's volumes to millilitres or its cups to grams for a specific ingredient removes this ambiguity entirely, and is one of the most common everyday reasons people reach for a unit converter rather than guessing and hoping the dish turns out right.

One converter for every category

Rather than bookmarking a separate tool for temperature, another for length and a third for volume, having every category in one place means the same familiar interface handles whatever measurement comes up next, without needing to remember which specialised site to visit for each one.

Private and instant

The converter runs entirely in your browser using internationally agreed, highly precise conversion definitions, so no data is sent to any server and results appear the instant you type. It works offline once the page has loaded, ready for whichever measurement needs translating next.