Unit converter
Select a category, pick your units, and enter a value to convert instantly.
Kilometre → Mile
Length
Mile → Kilometre
Length
Metre → Foot
Length
Foot → Metre
Length
Inch → Centimetre
Length
Centimetre → Inch
Length
Kilogram → Pound
Weight
Pound → Kilogram
Weight
Kilogram → Ounce
Weight
Gram → Ounce
Weight
Celsius → Fahrenheit
Temperature
Fahrenheit → Celsius
Temperature
Celsius → Kelvin
Temperature
Litre → Gallon (US)
Volume
Gallon (US) → Litre
Volume
Millilitre → Fluid Ounce (US)
Volume
Kilometre/hour → Mile/hour
Speed
Mile/hour → Kilometre/hour
Speed
About this tool
Unit errors are not merely embarrassing; they are expensive. NASA lost the Mars Climate Orbiter in 1999 because one team worked in pound-force seconds and another in newton seconds. Air Canada Flight 143 ran out of fuel at altitude in 1983 after a conversion between pounds and kilograms went the wrong way. The risk is highest exactly where it feels lowest — familiar everyday quantities converted casually. Two properties of unit conversion cause most of the trouble. First, most conversions are pure multiplication, but temperature is not: Celsius and Fahrenheit have different zero points, so converting a temperature difference is a different operation from converting a temperature. Second, some unit names are not unique. A US gallon is 3.785 litres and an imperial gallon is 4.546, a difference of twenty percent; US and imperial fluid ounces, pints, and tons all differ similarly. This converter handles length, weight, temperature, volume, speed, and area using standard internationally agreed factors, and it runs entirely in your browser.
- 1
Select a category — length, weight, temperature, volume, speed, or area.
- 2
Choose your source unit and target unit from the dropdowns.
- 3
Enter your value — the conversion result appears instantly.
- 4
Swap the units with one click to reverse the conversion.
Convert kilometres to miles or metres to feet when working across metric and imperial systems.
Quickly convert Celsius to Fahrenheit or Kelvin for science, cooking, or weather data.
Convert kilograms to pounds or litres to gallons for recipes, shipping, or travel.
Kilometres to miles
100 km62.14 milesCelsius to Fahrenheit
37°C98.6°FKilograms to pounds
70 kg154.32 lbsA temperature difference converts incorrectly
Cause: Converting a temperature uses the full formula including the offset, but converting an interval must not. A rise of 10°C is a rise of 18°F, not 50°F.
Fix: For a difference, multiply by 1.8 with no offset. This converter treats input as an absolute temperature, which is what you want for a reading and not what you want for a delta.
The volume result is off by about twenty percent
Cause: US and imperial gallons, pints, and fluid ounces share names but not sizes. A recipe, fuel figure, or spec sheet rarely says which system it means.
Fix: Establish which system the source used before converting. US measures are standard in American recipes and fuel economy figures; imperial measures persist in the UK for fuel and draught beer.
Rounded results accumulate error across a calculation
Cause: Each displayed result is rounded for readability. Chaining conversions — feeding a rounded output back in as the next input — compounds that rounding at every step.
Fix: Convert once, directly from the source unit to the target unit, rather than hopping through intermediate units. Keep full precision through a calculation and round only the final figure.
These answers explain common unit converter tasks, expected input formats, and edge cases so both visitors and search engines can understand what this tool does.
Which unit categories are supported?
This tool supports Length, Weight, Temperature, Volume, Speed, and Area — covering the most common conversion needs for everyday and technical use.
How accurate are the conversions?
Conversions use standard internationally accepted factors. Results are shown to up to 8 significant figures, which is sufficient for most practical purposes.
Why is temperature conversion different from other units?
Temperature scales like Celsius, Fahrenheit, and Kelvin use offset formulas rather than simple multiplication factors, so they require separate conversion logic.
Which unit categories does this converter support?
Length (metres, kilometres, miles, feet, inches), weight (kilograms, pounds, ounces, grams), temperature (Celsius, Fahrenheit, Kelvin), volume (litres, gallons, millilitres, fluid ounces), speed (km/h, mph, m/s), and area (square metres, square feet, acres, hectares).
How do I convert kilometres to miles?
Select the Length category, set the input unit to Kilometres and the output unit to Miles, then enter the value. One kilometre equals approximately 0.621371 miles. The same approach works for any supported unit pair.