Unit Converter

About Unit converter

Converts values between metric, imperial and a few niche units across nine categories: length, mass, area, volume, speed, pressure, energy, power and time. Two linked boxes let you type on either side, and a table underneath shows the same value in every unit of the category.

How to use it

1. Choose a category from the Measurement type menu. It opens on Length, and each category loads a sensible pair of units.
2. Type a value into the From box and pick its unit; the To box fills in on its own.
3. Change the To unit, press Swap to flip the direction, or type in the To box to convert backwards.
4. Copy the result line, or scroll to the All units table to see every unit at once.

A marathon in kilometers

26.2 mi

42.1648 km

When to use it

• Converting a recipe or hardware spec that mixes inches, millimeters and pounds.
• Comparing tire pressure in psi with a gauge that reads in bar.
• Turning an energy label in kilojoules into the food calories on a nutrition plan.
• Checking a car's power quoted in kilowatts against horsepower ratings.

Questions about Unit converter

How many digits does it show?

Six significant figures, without trailing zeros. Values at or above 1e15 or below 1e-6 switch to exponential form so nothing collapses to zero.

Are US and imperial gallons kept apart?

Yes, they are separate units. The US gallon is exactly 231 cubic inches, or 3.785411784 liters, and the imperial gallon is exactly 4.54609 liters.

Why does Mach carry a warning?

Sound travels at different speeds depending on temperature. The tool uses 340.29 meters per second, the sea-level value at 15 degrees Celsius, and says so next to the result.

How are months and years defined?

A month is the Gregorian average of 30.436875 days and a year is the Julian 365.25 days. They are averages, not calendar months, and the tool notes it.

Where is temperature?

It has its own page, because temperature scales use offsets rather than a single multiplier. The Temperature converter covers Celsius, Fahrenheit, Kelvin, Rankine and Reaumur.

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