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Quick guide
Understand the calculation
Convert a length, an area or a volume to another unit of the same type, across 46 units. These include nanometres (nm), ångströms (Å), inches, hectares, acres, litres, US and imperial gallons, and more. Below the result, see the equivalence between the two chosen units, for example 1 cm² = (10 mm)² = 100 mm².
When to use this tool
Use it to convert wavelengths or distances in crystals between nanometres (nm), ångströms (Å) and picometres (pm); areas from cm² to m²; or lab volumes from mL to µL or cm³. You can also express land areas in hectares, ares (a) or acres, and convert inches, feet, gallons or fluid ounces to metric units. On each discipline's page, you can open it as a floating bubble to keep it at hand while using a calculator.
How the conversion works
Choose length, area or volume, type only the number and select the unit of the value and of the result. The conversion updates instantly. Swapping units keeps the number you typed. For areas, the conversion factor applies twice: since 1 m = 100 cm, 1 m² = (100 cm)² = 10000 cm². For volumes, it applies three times: 1 m³ = (100 cm)³ = 10⁶ cm³. A millilitre is one thousandth of a litre: 1 L = 1 dm³, 1 mL = 1 cm³ and 1 µL = 1 mm³. In the relation below the result, = means an equivalence without rounding and ≈ means an approximation. For example, 1 in² = (2.54 cm)² = 6.4516 cm². Choose 6 or 10 significant figures: these are the digits kept when rounding the result. You can also type a decimal comma or point and use scientific notation: 2.5e-3 means 0.0025. Very large or very small results appear in scientific notation. “Show all equivalents” lists the same value in the other units of the chosen type.
The tool changes units of length, area or volume; it does not calculate the area or volume of a shape. To convert a volume to a mass, use Density, Mass and Volume. Foot, inch, yard and mile are the international ones. The US survey foot, cups, spoons, pints, quarts and US dry measures are not included. Type only the number and choose the unit next to it: entries such as “12 cm”, “1/2” or “5 ft 3 in” are not accepted. If a result is too large or too close to zero to display in the chosen unit, “—” appears; try another unit or check the available equivalents.
Verified examples
- Wavelength · 532 nm
532 nm = 5320 Å = 532000 pm - Area · 1 m² to cm²
1 m² = (100 cm)² = 10000 cm² - Land · 1 acre
1 acre = 4046.8564224 m² = 0.40468564224 ha - Lab · 250 µL
250 µL = 0.25 mL = 250 mm³ - Gallons · US and imperial
1 gal (US) = 3.785411784 L; 1 gal (imp.) = 4.54609 L
Frequently asked questions
Why is 1 m² equal to 10000 cm² and not 100?
Because both sides need converting: a square with sides of 1 m measures 100 cm by 100 cm, or 10000 cm². For volume, all three dimensions need converting: 1 m³ = 100 × 100 × 100 cm³ = 10⁶ cm³. That is why multiplying by 100 only once is not enough. The relation below the result shows how the change of unit applies.
Is 1 mL the same as 1 cm³?
Yes, exactly. A litre equals one cubic decimetre: 1 L = 1 dm³. The prefix “milli” means one thousandth of a litre, so 1 mL = 0.001 L = 1 cm³ = 10⁻⁶ m³. Also, 1 µL = 1 mm³. The capital L symbol avoids confusing a lowercase l with the digit 1.
Which gallon does it use: US or imperial?
You can choose either. The US gallon is the liquid one: 231 in³ = 3.785411784 L. The imperial gallon is 4.54609 L, about 20 % more. Their fluid ounces are different too: the US fluid ounce is 1/128 of its gallon (29.5735295625 mL) and the imperial one is 1/160 of its gallon (28.4130625 mL). US dry measures are not included.
Which foot and which mile does it use?
The international ones: 1 in = 2.54 cm, 1 ft = 0.3048 m, 1 yd = 0.9144 m and 1 mi = 1609.344 m, all exact. The US survey foot is a different unit used in historical data and is not on the list. The nautical mile (nmi) is another unit too: exactly 1852 m, about 1.15 miles.