Unit Converter

What this converter does

This converter switches between units in nine categories: length, weight, temperature, speed, volume, area, digital storage, pressure and energy. Type a number on either side and the other side updates instantly, so you can convert in both directions without swapping fields.

How to use it

1. Pick a category at the top, such as Volume.
2. Choose the unit you have in the From list and the unit you want in the To list.
3. Type your number in either box. The swap button flips the two units.

How the conversion works

Every unit in a category is stored as a multiple of one base unit (meters for length, grams for weight, liters for volume, and so on). To convert, the tool turns your value into the base unit and then into the target unit:

result = value × factor_from ÷ factor_to

Temperature is the exception: Celsius, Fahrenheit and Kelvin start from different zero points, so they need an offset as well as a multiplier:

°F = °C × 9/5 + 32     K = °C + 273.15

Exact definitions behind the numbers

Many everyday units are defined exactly in metric terms, according to the US National Institute of Standards and Technology (NIST):

Unit	Equals	Exact?
1 inch	2.54 cm	Yes
1 mile	1,609.344 m	Yes
1 UK (imperial) gallon	4.54609 L	Yes
1 US gallon	3.785412 L	231 cubic inches exactly
1 US fluid ounce	29.57353 mL	Derived from the gallon
1 knot	0.5144444 m/s	1 nautical mile per hour
1 mmHg	133.3224 Pa	Conventional value

Cooking measures: US, UK or metric?

Recipes from different countries use spoons and cups of different sizes, which is why the volume list names each one:

• US: teaspoon 4.93 mL, tablespoon 14.79 mL, cup 236.6 mL
• Metric (Canada, New Zealand, the UK and much of Europe): teaspoon 5 mL, tablespoon 15 mL, cup 250 mL. Australia uses a 20 mL tablespoon
• The UK fluid ounce (28.41 mL) is smaller than the US fluid ounce (29.57 mL), but the UK pint (568 mL) is larger than the US pint (473 mL), because a UK pint has 20 fluid ounces and a US pint has 16.

For most recipes the US and metric spoons are close enough to swap. For baking, where precision matters, convert carefully or weigh ingredients instead.

Digital storage: why 1 KB = 1,024 bytes here

This converter uses binary multiples, where each step is 1,024 times the last. That's the convention most operating systems use when they report file and disk sizes. Drive manufacturers use decimal multiples (1 kB = 1,000 bytes), which is why a "1 TB" drive shows as about 931 GB on a computer.

Frequently asked questions

Why is precision important?

Small rounding errors add up in engineering, medicine and baking. This tool keeps up to 10 decimal places and trims trailing zeros.

What's the difference between imperial and metric?

Metric units scale by tens and are used by most of the world. Imperial and US customary units, such as inches, pounds and gallons, are used mainly in the United States, with some still in everyday use in the UK.

Is Mach a fixed speed?

No. Mach 1 is the speed of sound, which changes with air temperature. This tool uses 340.29 m/s, the standard value at sea level and 15 °C.

Can I convert weight to volume?

Not directly. That depends on the density of the ingredient or material: a cup of flour weighs much less than a cup of water.

Related tools: BMI Calculator and Coffee Ratio Master.

Sources: NIST Special Publication 811, Appendix B.8: Factors for units listed alphabetically. Last reviewed on SuiteWebTools: October 2026.