Unit Converter
Convert between metric and imperial units of length, weight, volume and temperature instantly.
Privacy: This tool runs entirely in your browser. Your data never leaves your device and is never uploaded to any server.
Result
0.393701 inch
How to use this unit converter
- Pick a category: length, weight, volume or temperature.
- Choose the units to convert between, or use Swap to reverse them.
- Type a value and read the result as you type.
- Copy the answer with one click; nothing is uploaded.
Metric and imperial, side by side
| Quantity | Metric | Imperial or US | Exact factor |
|---|---|---|---|
| Length | 1 metre | 3.281 feet | 1 foot = 0.3048 m exactly |
| Length | 2.54 centimetres | 1 inch | 1 inch = 25.4 mm exactly |
| Weight | 1 kilogram | 2.205 pounds | 1 pound = 0.45359237 kg exactly |
| Weight | 28.35 grams | 1 ounce | 1 ounce = 28.349523125 g exactly |
| Volume | 3.785 litres | 1 US gallon | 1 US gallon = 231 cubic inches |
| Volume | 1 litre | 4.227 US cups | 1 US cup = 236.588 mL |
Temperature is not a simple ratio
Doubling 10 degrees Celsius does not give you 20 degrees Fahrenheit, because the two scales do not start at the same zero.
Celsius and Fahrenheit are offset from each other, and Kelvin starts at absolute zero entirely. That is why temperature needs a conversion formula where length only needs a multiplication.
Where unit conversions go wrong
- Mixing US and UK gallons, pints or fluid ounces — they differ by around 20%.
- Treating ounces by weight and fluid ounces by volume as the same thing; they are not.
- Rounding in the middle of a calculation rather than at the end.
- Assuming a tonne is a US ton: a metric tonne is 1,000 kg, a US short ton is 907 kg.
Frequently asked questions
How accurate are the conversions?
They use the exact defined factors — an inch is defined as exactly 25.4 mm — so rounding only happens when the result is displayed.
How many decimal places are shown?
Up to six, with trailing zeros trimmed. The full value is kept for anything you convert next.
Is the gallon US or imperial?
US. A US gallon is 3.785 litres and a UK gallon is 4.546 litres, so check which one a recipe or specification means.
Why is temperature handled differently?
Length and weight convert by multiplying by a factor. Temperature scales have different zero points, so they need a formula rather than one number.
Does it handle very large or very small values?
Yes, within the limits of double-precision floating point. Beyond that you want scientific notation.
Is anything uploaded?
No. The conversion is arithmetic in your browser and nothing is sent anywhere.
More Number & Time tools
Number Base Converter
Convert numbers between binary, octal, decimal and hexadecimal with BigInt support for arbitrarily large values.
Unix Timestamp Converter
Convert Unix timestamps to human-readable dates and back, in seconds or milliseconds.
Percentage Calculator
Work out a percentage of a value, what percent one number is of another, and percentage increase or decrease.
Age Calculator
Work out an exact age in years, months and days, plus total days lived and time until the next birthday.