Unit converter
This unit converter recalculates a value between units in four categories: length, weight, temperature and volume. Pick a category, type a number, choose the "from" unit and the "to" unit, and the result appears instantly. It handles metres and miles, kilograms and pounds, degrees Celsius, Fahrenheit and Kelvin. Everything runs directly in your browser — nothing is sent anywhere.
How the unit converter works
For length, weight and volume the tool works with a so-called base unit. Every unit has a conversion factor relative to this base: for length the base is the metre (m = 1), for weight the kilogram (kg = 1) and for volume the litre (l = 1). Conversion then happens in two steps — the input value is first multiplied by the factor of the source unit (converting it to the base unit) and then divided by the factor of the target unit. The result is rounded to five decimal places.
The specific factors follow international definitions: 1 mile = 1609.344 m, 1 foot = 0.3048 m, 1 inch = 0.0254 m, 1 pound = 0.45359237 kg, 1 ounce = 0.0283495 kg, 1 US gallon = 3.78541 l.
Temperature is handled differently, because the scales do not start at the same zero. The tool therefore first converts the input to degrees Celsius and only then to the target scale. It uses the formulas °F to °C: (°F − 32) × 5/9, and °C to °F: °C × 9/5 + 32; Kelvin is °C + 273.15.
How to use the unit converter
- In the Category dropdown choose what you want to convert — length, weight, temperature or volume.
- Type the number you want to convert into the value field.
- In the first selector pick the unit you convert from, and in the second the unit you convert to.
- The result appears instantly next to the units — no need to confirm anything.
Conversion examples:
| Input | From | To | Result |
|---|---|---|---|
| 5 | km | mile | 3.10686 |
| 10 | inch | cm | 25.4 |
| 100 | °F | °C | 37.77778 |
What the unit converter is good for
The converter is handy when cooking from foreign recipes (ounces, gallons), reading technical specs in inches and feet, travelling and converting temperatures between °C and °F, or at school with physics and maths problems. It also helps tradespeople and DIYers who run into imperial measurements.
Because the entire calculation runs locally on your device, the values you enter never leave the browser — the tool needs no server connection or registration and works offline too. For everyday use, five-decimal precision is more than enough; for scientifically demanding calculations, keep the rounding in mind.
FAQ
How many centimetres is one inch?
Exactly 2.54 cm. The inch is internationally defined as 0.0254 metre, so 1 inch = 2.54 cm and, for example, 10 inches = 25.4 cm.
Which gallon does the tool use — US or British?
The tool uses the US gallon of 3.78541 litres. The British imperial gallon (4.54609 l) is not included, so results won't match British recipes.
How do I convert Fahrenheit to Celsius?
Choose the Temperature category, set °F as the source and °C as the target unit. The tool uses the formula (°F − 32) × 5/9. For example, 100 °F is roughly 37.78 °C.
Are the numbers I enter sent to any server?
No. The whole conversion runs directly in your browser using JavaScript. No value is sent anywhere, the tool needs no registration and works without an internet connection.
Why is the result rounded?
The tool rounds to five decimal places so the output stays readable and doesn't show long "tails" caused by floating-point rounding errors. For everyday use this precision is sufficient.
Does the tool distinguish mass and weight?
The tool works with mass (kg, g, t, pound, ounce) in the everyday sense. It doesn't address the physical difference between mass and weight (force) — for daily kilogram and pound conversions that isn't relevant.
Can the converter handle temperature in Kelvin?
Yes. In the Temperature category, alongside °C and °F there is also Kelvin (K). Conversion to Kelvin is computed as °C + 273.15, so for example 0 °C equals 273.15 K.
Can I convert speed, pressure or area?
No, currently the tool supports four categories: length, weight, temperature and volume. Other quantities such as speed, pressure or area are not yet included.
📅 Last updated: 16 July 2026