Welcome to ConversionFrom.com
Convert between any two units of the same kind, see the formula behind the result, and read what each unit actually measures.
Pick a converter below, or type the conversion straight into the address bar. Every pair has a page of its own, with the formula written out, a worked example and a table of the values people reach for most. And if you want to know what a unit actually is rather than only what it converts to, it has a page in the dictionary as well.
Try our unit converters
How our unit converters work
Choose the two units, type a value, and the answer appears as you type — there is nothing to submit and nothing to wait for. One click inverts the pair, so kilograms to pounds becomes pounds to kilograms without leaving the page. Units are listed under their full names as well as their symbols, so there is never any doubt about which tonne or which gallon you have picked.
The arithmetic happens in your browser, in decimal rather than binary floating point, so what you read is the result of the sum and not an artefact of how computers store fractions. Every converter also shows its formula in words — what to multiply by, what to add or subtract — followed by a worked example and a table of the same conversion at the values people actually type: one, two, five, ten, twenty-five, a hundred. You never have to take the result on trust.
A conversion is only as good as the number behind it. Every ratio on this site is stored as the unit’s own definition rather than as a rounded factor copied from someone else’s table: the inch is exactly 2.54 centimetres, the imperial gallon is exactly 4.546 09 litres, and the cubic inch is exactly 1.6387064 hundred-thousandths of a cubic metre. Those definitions are checked in bulk against their standard values, so a mistyped digit or a wrong divisor is caught before it can reach a page and be read, quietly and wrongly, a hundred thousand times.
The addresses of those pages are meant to be typed as well as clicked. Ask for meters-to-inches and you convert one metre; ask for 25-meters-to-inches and you convert twenty-five; ask for m-to-in and the symbols take you to the same page. Any pair can be inverted without reloading, and every spelling of a pair points at one canonical page, so you are never reading a thin copy of the page you actually wanted.
Popular conversions
These are the pairs people ask for most: kilograms to pounds, centimetres to inches, Celsius to Fahrenheit, kilometres to miles. Every figure below is worked out from the units’ own definitions rather than copied off a table, and each card opens the full converter for that pair. If the one you want is not here, every unit on the site converts to every other unit of its kind, in either direction.
A dictionary, not only a calculator
Most conversion sites stop at the number. This one has a written page for every single unit it converts. Each explains what the unit measures, where it came from, who fixed its value and when, where it is still used today, and what people most often get wrong about it — why a furlong is an eighth of a mile, why network speeds are quoted in bits while file sizes are quoted in octets, why a pint means one thing in London and another in Chicago.
Every page here exists in eleven languages, and that means the pages themselves rather than a machine pass over the English. Unit names are translated wherever a language has its own; the addresses stay in English, so a link you send still works whichever version the person opens.
Every one of those pages ends with a conversion table against all the other units of the same kind, generated from the same definitions the calculator uses, so the dictionary and the converter can never drift apart. From any unit you can step sideways to the others that measure the same quantity, or up to the measurement system it belongs to.
All length units All mass units All temperature units All energy units All volume units All speed units All time units All data units All pressure units All frequency units All data-transfer rate units All volumetric flow rate units All angle units All area units
