Free Unit Converter — Length, Weight, and Temperature

Unit conversion is the process of expressing the same physical quantity in a different measurement unit. It matters whenever data from different systems needs to be compared or combined — a recipe using cups alongside one using millilitres, or engineering drawings in millimetres versus inches.

The conversion factor method works by multiplying the original measurement by a fraction that is equal to 1. For example, since 1 inch equals 2.54 centimetres, multiplying by (1 in / 2.54 cm) converts centimetres to inches without changing the underlying quantity — you are simply rescaling. Most conversions in this tool use this approach, with factors accurate to at least 6 significant figures.

Temperature is the exception. Celsius, Fahrenheit, and Kelvin do not share the same zero point, so a simple multiplication factor cannot bridge them. Instead the converter applies a two-step formula: first shifting the value to a common reference (Celsius is used internally), then rescaling to the target scale. That is why 0 °C is 32 °F, not 0 °F.