How this calculator works
This page groups five common kinds of conversion in one place. Each category converts through a single base unit: metres for length, square metres for area, cubic metres for volume, kilograms for mass and kelvin for temperature. Length, area and volume factors follow from the exact international definitions of the inch and foot. Temperature is different because its scales have offsets as well as different sizes of degree, so the calculator uses the full affine conversion rather than a simple ratio.
Formula
result = value x F(from) / F(to) for linear units, where F is the base-unit size of a unit. For temperature: K = C + 273.15, K = (F - 32) x 5/9 + 273.15, and C = (F - 32) x 5/9. The full table applies the same conversion to every unit in the category.
Worked example
5 cm is 1.96850 inches and 0.05 m. 1 acre is 4,046.86 m2. 2 L is 0.528344 US gallons. 70 kg is 154.324 lb. 100 °C is 212 °F and 373.15 K.
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Frequently asked questions
Why is temperature in the same calculator as length?
They are both common everyday conversions, and grouping them saves a search. The maths is different, because temperature scales have different zero points, but the interface and the full table are the same.
Are US and imperial gallons both shown?
Yes. The volume list includes the US gallon, the imperial gallon, US quarts, pints, fluid ounces, cups, tablespoons and teaspoons. The imperial gallon is larger, at 4.54609 L against 3.785411784 L.
Does the table round each value?
Yes, to six significant digits. The underlying calculation keeps full precision, so chained conversions should use the original value rather than a rounded table entry.