Unit Converter
Convert length, weight, and temperature units.
Converting between units of measurement
This unit converter covers the conversions that come up most often in daily life and in coursework — length, weight, temperature and volume — switching between metric and imperial in both directions. Every conversion except temperature is a simple multiplication by a fixed factor; temperature needs an offset as well, which is why it is the one people get wrong.
How to use the Unit Converter
- Choose the Type of measurement.
- Enter the Value.
- Pick the units to convert From and To.
- The converted value appears immediately.
Formula and a worked example
Length: 1 inch = 2.54 cm · 1 mile = 1.60934 km
Weight: 1 kg = 2.20462 lb
Temperature: °F = °C × 9/5 + 32 · °C = (°F − 32) × 5/9
Length, weight and volume are ratio scales — zero means zero in both systems, so a single multiplier works. Temperature is an interval scale with different zero points, so it needs the offset of 32 as well as the ratio.
Worked example
Converting 180 cm gives 70.87 inches, or 5 feet 11 inches. Converting 25 °C gives 77 °F — and note that halving 25 °C to 12.5 °C does not halve the Fahrenheit figure, precisely because of that offset.
Frequently asked questions
How do I convert cm to inches?
Divide by 2.54. So 180 cm ÷ 2.54 = 70.87 inches.
Why is temperature conversion different?
Because the Celsius and Fahrenheit scales start from different zero points. You need both a ratio and an offset, not just a multiplier.
How many kilometres is a mile?
1.60934 km. A quick mental shortcut is to multiply miles by 1.6, or by 8 and divide by 5.
Is a US gallon the same as a UK gallon?
No. A US gallon is about 3.785 litres, an imperial gallon about 4.546 — a difference of roughly 20%.
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