Unit Converter
Free unit converter for length, weight, temperature, volume, speed, and digital storage. Instant, accurate, no signup.
What the unit converter covers
It converts between units in six categories — length, weight, volume, speed, data, and temperature — by changing one input and reading the output live. Because it works in both directions and has a swap button, it handles the everyday conversions that come up in cooking, travel, study, and DIY without a lookup table. Every category runs from a base unit, so any unit in a category converts to any other.
How the conversion works
- Most categories convert by factors: the value is divided by the from-unit’s factor to reach the base unit, then multiplied by the to-unit’s factor. Length uses the metre as its base, weight the kilogram, volume the litre, speed metres per second, and data the byte.
- Temperature needs formulas rather than simple factors: F = C × 9/5 + 32, and K = C + 273.15, applied through Celsius as the hub.
- Data units are binary, not decimal: 1 KB is 1,024 bytes, 1 MB is 1,024 KB, and so on. This is the value a computer reports.
Worked examples
| Conversion | Result |
|---|---|
| 1 km → m | 1,000 m |
| 10 km → mi | 6.2137 mi |
| 70 kg → lb | 154.3236 lb |
| 1 US gallon → L | 3.78541178 L |
| 100 km/h → mph | 62.1371 mph |
| 1 GB → MB | 1,024 MB |
| 100°C → °F | 212°F |
Reference conversions worth memorising
| Metric | Imperial / US |
|---|---|
| 1 kilometre | 0.6214 miles |
| 1 inch | 2.54 centimetres |
| 1 kilogram | 2.2046 pounds |
| 1 stone | 6.3503 kilograms |
| 1 litre | 0.2642 US gallons |
| 1 metre per second | 3.6 km/h |
Common mistakes
- Mixing up US and imperial gallons. A US gallon is 3.785 litres; an imperial gallon is 4.546 litres. The converter uses US liquid measures for gal, qt, pt, cup, and fluid ounces.
- Reading KB as 1,000 bytes. In this converter, and in most software, storage uses powers of 1,024. Drive manufacturers sometimes use decimal units, which is why a “1 TB” drive shows less in your operating system.
- Treating weight and mass as identical. Kilograms and pounds here are mass units; the tools use them interchangeably for everyday weight, which is fine outside scientific work.
- Forgetting temperature is not a simple factor. You cannot multiply Celsius into Fahrenheit, because the scales have different zero points — the converter applies the correct formula.
- Converting fluid ounces by weight. A fluid ounce measures volume; an ounce measures mass. They are different units with the same name.
Frequently asked questions
Why is 1 GB only 1,024 MB and not 1,000?
Because digital storage is built on powers of two. A kilobyte is 210 bytes (1,024), and each step multiplies by 1,024 again. Decimal prefixes are used for marketing, which is the source of the “missing capacity” on a new drive.
How do I convert a height in feet and inches to centimetres?
Convert the feet to inches (multiply by 12), add the extra inches, then multiply the total by 2.54. Someone 5 ft 9 in is 69 inches, or 175.26 cm. For health measures built on height, the BMI calculator accepts either system directly.
Is a metric tonne the same as a US ton?
No. A metric tonne is 1,000 kg (about 2,204.6 lb), while a US short ton is 2,000 lb (about 907.2 kg). They are close enough to confuse in conversation and different enough to matter in freight.
Can I convert between categories, like litres to kilograms?
Not directly, and the tool will not try. Volume and mass are different quantities; the link between them depends on what the substance is — a litre of water weighs about a kilogram, but a litre of oil does not. Convert within a category, then apply the substance’s density if you need to cross over.
Some conversions are really number-base changes rather than unit changes. For those, a number base converter handles binary, octal, decimal, and hexadecimal directly.