How precise are the results?

Each value is rounded to 6 significant figures, enough for cooking, travel, and most engineering checks: 5 km shows as 3.10686 mi. Values below 0.001, or at 1 quadrillion and above, switch to scientific notation, such as 2.36588e-4. The factors behind them are exact definitions where one exists, so rounding happens only on display. The copy icon copies the value exactly as shown, comma separators included.

Unit Converter

Type a value with units — get every conversion.

Type a value like 5 km or 32 psi

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nmi

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How to use Unit Converter

Type a number followed by its unit, for example 5 km, 12oz, 72 f, or 1.5e3 m. The space is optional.
Check the line under the box. It shows what was detected, such as Detected: Length · Kilometers, and the matching tab is selected for you.
Read the cards below: every unit in that category, rounded to 6 significant figures.
Click the copy icon on any card to copy that value.
Use the tabs (Length, Area, Volume, Mass, Temperature, Pressure, Speed) to see which units each category covers.

01 · Real-world fits

Common use cases

Turning a US recipe's 0.75 cup into milliliters for a metric measuring jug
Checking a tire pressure of 2.4 bar against a 35 psi spec (2.4 bar is 34.8 psi)
Reading a European weather forecast: 28 c is 82.4 °F
Converting a 10 km race to miles (6.21371 mi) or a speed limit in km/h to mph
Working out how many acres a 2-hectare lot is (4.94211 ac)
Giving your weight in kg, pounds, and stone for a UK form

02 · The honest pitch

Why Unit Converter?

There are no from and to dropdowns. You type the value the way you would say it, and the converter finds the unit and fills in every conversion in that category, so 5 km gives you meters, feet, miles, and nautical miles in one look. It understands common aliases like lbs, kph, klick, and sq ft, plus scientific notation. Conversion factors use the exact defined values (1 inch = 2.54 cm, 1 lb = 0.45359237 kg, 1 US gallon = 3.785411784 L), and your last input comes back if you reload the tab.

03 · Edge cases

Frequently asked questions

How do I convert Celsius to Fahrenheit?

Multiply by 9/5 and add 32: °F = °C × 1.8 + 32. Going the other way, °C = (°F − 32) × 5/9. Temperature is the one category where you can't just multiply, because the scales start at different zero points. Type 37 c and you get 98.6 °F and 310.15 K. A handy check: −40 is the same in both scales.

How many pounds are in a kilogram?

What's the difference between psi, bar, and atm?

Is a US cup the same as a metric cup?

Why does nm give nautical miles and not nanometers?

What input formats does it accept?