How it works
Each unit is converted through one base unit (millimetre, square metre, litre or kilogram) with exact defined factors: 1 in = 25.4 mm, 1 lb = 0.45359237 kg, 1 US gallon = 3.785411784 l, 1 imperial gallon = 4.54609 l.
Results are rounded for display to seven significant digits; the calculation itself is not rounded.
What the calculator assumes
- Gallons, quarts and fluid ounces differ between the US and the UK; both are listed separately.
- Weight here means mass (kg, lb), as shown on scales and packaging.
Questions
- How many millimetres is one inch?
- Exactly 25.4 mm. One foot is exactly 304.8 mm.
- How many litres is one cubic metre?
- Exactly 1,000 litres.
Planning aid only. It does not size structural members or check loads — follow the manufacturer's instructions and your local building rules.