Unit Conversion: Length, Area, Volume and Temperature

Write the source number and its unit before converting. Length, area and volume use different factors, even when their unit names look similar.

Length: multiply once

One inch is exactly 25.4 millimetres, so 12 inches is 304.8 mm. One foot is 0.3048 metres. The Length Converter helps compare supported linear units; check whether a drawing uses inches, feet, millimetres or centimetres.

Area: square the factor

Since one metre is 100 centimetres, one square metre is 100 × 100 = 10,000 square centimetres. One square foot is 0.3048 × 0.3048 = 0.09290304 square metres. Use the Area Converter for area values rather than applying a length conversion once.

Volume: cube the factor

One cubic metre is 1,000 litres. One cubic foot is approximately 28.3168 litres. For a rectangular space, first put length, width and height into the same units, then multiply them. Gross dimensions do not automatically give usable internal capacity when walls, braces or other objects occupy space.

The Volume Converter performs unit conversion. For gallons or fluid ounces, confirm whether the source uses US or imperial units; the same everyday name can refer to different quantities.

Temperature includes an offset

For a temperature reading, °F = °C × 9/5 + 32. Thus 25°C is 77°F. A temperature difference of 10°C, however, equals a difference of 18°F; do not add 32 to a difference. Use the Temperature Converter for ordinary readings.

Keep more digits during intermediate steps and round at the end to the precision your measurement supports. Unit conversion does not make an imprecise original measurement exact.