How the calculation works
The formulas
Choose a dimension first; incompatible unit pairs are rejected. Conversion multiplies by the source unit’s SI factor and divides by the target factor. Display rounding does not change the internal value.
Target value = source value × source SI factor ÷ target SI factor
1 ft = 0.3048 m; 1 in = 0.0254 m; 1 lb = 0.45359237 kg
Assumptions to check
- Feet and inches use international definitions, not US survey feet. Pounds and ounces are mass, not force.
- US liquid gallon = 3.785411784 L; imperial gallon = 4.54609 L. US short ton = 2,000 lb; imperial long ton = 2,240 lb.
A worked example
10 ft converts to exactly 3.048 m. One US liquid gallon converts to 3.785411784 L; one imperial gallon converts to 4.54609 L.