Britain runs on both systems at once — height in feet, weight in stone, distance in miles, but shopping in grams and litres. These are the conversions that come up.
Length
| From | To | Multiply by |
|---|---|---|
| Centimetres | Inches | ÷ 2.54 |
| Inches | Centimetres | × 2.54 |
| Metres | Feet | × 3.281 |
| Miles | Kilometres | × 1.609 |
| Kilometres | Miles | × 0.621 |
The working
How tall is 175 cm in feet and inches? 175 ÷ 2.54 = 68.9 inches 68.9 ÷ 12 = 5 feet, remainder 8.9 → 5 ft 9 in
A rough one worth carrying: miles to kilometres is close to multiplying by 1.6, and kilometres to miles is close to multiplying by 0.6. Good enough for a road sign, not for anything you are being billed for.
Weight
| From | To | Multiply by |
|---|---|---|
| Kilograms | Pounds | × 2.205 |
| Pounds | Kilograms | × 0.4536 |
| Kilograms | Stone | ÷ 6.35 |
| Stone | Kilograms | × 6.35 |
A stone is 14 pounds. British weights are usually spoken as stone and pounds together — 11 st 7 lb — which is 161 pounds, or 73 kg.
Volume — and the pint problem
A UK pint is 568 ml. A US pint is 473 ml. That is a 20% difference, and it runs through every liquid measure — gallons, quarts and fluid ounces all differ between the two systems. American recipes are a common way to be caught out.
| From | To | Multiply by |
|---|---|---|
| Litres | UK pints | × 1.760 |
| UK pints | Litres | × 0.568 |
| Litres | US pints | × 2.113 |
| Litres | UK gallons | × 0.220 |
| Litres | US gallons | × 0.264 |
Temperature
Temperature is the odd one out: it has an offset as well as a scale, because the two scales do not start from the same place.
The working
°F = (°C × 9/5) + 32 °C = (°F − 32) × 5/9 20°C → (20 × 1.8) + 32 = 68°F 100°F → (100 − 32) × 5/9 = 37.8°C
The mental shortcut: double it and add 30. 20°C gives 70, against a true 68. Close enough for weather, useless for an oven.
−40 is the same in both scales. It is the one point where the two lines cross, and it is a genuinely useful check that you have the formula the right way round.
Common questions
How many cm is 5 foot 9?
175.3 cm. Convert the whole height to inches first — 5 × 12 = 60, plus 9 makes 69 inches — then multiply by 2.54, giving 175.26 cm. Converting the feet and the inches separately and adding them works too, but is easier to get wrong.
How many kg is 11 stone?
69.9 kg. A stone is 14 pounds, so 11 stone is 154 pounds, and 154 × 0.4536 = 69.85 kg. The quicker route is to multiply the stone straight by 6.35, which gives the same answer in one step.
Why is a US gallon smaller than a UK one?
They descend from different historical standards. The US kept an older English wine gallon; Britain redefined its gallon in 1824 as the volume of ten pounds of water. The US gallon is 3.785 litres, the UK gallon 4.546 — a 20% gap that also explains the pint difference.
Is a metric tonne the same as a ton?
No, but they are close. A metric tonne is 1,000 kg. A UK long ton is 1,016 kg and a US short ton is 907 kg. For most purposes the difference is small enough to ignore and large enough to matter if you are paying by weight.
Check this before you rely on it. A free guide to everyday arithmetic — not tax, accounting, financial, legal or medical advice. The working is shown above so you can verify it against your own figures. See our terms of use.