Unit Converter

A UK gallon is about 4.546 litres, a US gallon is about 3.785 litres. So a US gallon is roughly 83% of a UK gallon. Recipe books and fuel economy figures from the US and UK use different gallons — if you don't notice, you'll over-pour by about 20%. The calculator separates them clearly.

Quick mode shows up to 6 significant decimal places — enough for science and engineering. For everyday cases (cooking, car distances) the first 2-3 places are all you need. Customize mode lets you pick 2 / 3 / 4 / 6 / 8 decimal places.

The international inch was standardised in 1959 at exactly 25.4 mm. Every imperial length conversion (foot, yard, mile) ultimately derives from that single number. Before 1959 the inch varied slightly between the US and UK; this is a useful piece of trivia, not a real engineering concern today.

Food labels use kilocalories (often labelled 'Calories' with a capital C — they're the same as kcal). Electricity bills use kilowatt-hours (kWh). Heating systems use BTU (especially in the US). Science papers use joules. The calculator handles all five plus calories (small) and watt-hours.

We use the binary prefix (1 KB = 1024 B) because that's what most software and storage devices actually use. Some marketing materials use decimal (1 KB = 1000 B), which is why a '1 TB' drive shows ~931 GB in your OS. If you specifically need decimal multiples, divide by 1.024^n.

1 ton of refrigeration = 12,000 BTU per hour ≈ 3,517 watts. The name comes from the energy needed to melt one short ton of ice in 24 hours. A 1.5-ton AC unit cools at 18,000 BTU/h — typical for a UAE bedroom. A 2-ton unit handles a larger living room.

We cover the 10 most-converted everyday categories. If you need something specialised (engineering torque, electric capacitance, radiology dose, etc.), search for a dedicated converter — those domains have unit ecosystems too deep for a general tool.