Unit Converters guide
Kilograms, Pounds, Stone and Tons: A Practical Guide
· 3 min read
One kilogram is about 2.2046 pounds, and one pound is exactly 0.45359237 kg. For body weight in the UK and Ireland, one stone is 14 pounds, or about 6.35 kg. Those three facts handle most everyday weight conversions; the rest of this guide walks through the situations where people actually need them, and the traps around ounces and tons.
Which conversion factors are exact?
| Unit | In kilograms | Exact? |
|---|---|---|
| Pound (lb) | 0.45359237 | Yes, by definition |
| Ounce (oz) | 0.028349523125 | Yes (1/16 lb) |
| Stone (st) | 6.35029318 | Yes (14 lb) |
| US ton (short) | 907.18474 | Yes (2,000 lb) |
| UK ton (long) | 1,016.0469088 | Yes (2,240 lb) |
| Metric ton (t) | 1,000 | Yes |
| Carat (ct) | 0.0002 | Yes (200 mg) |
The approximate one is the reverse: 1 kg ≈ 2.204622622 lb. "Multiply by 2.2" is fine for a quick estimate, about 0.2% off.
Scenario 1: Packing for a flight
Many airlines quote a checked-bag limit of 23 kg or 50 lb as if they were the same. They are close but not identical: 23 kg is 50.71 lb, and 50 lb is 22.68 kg. If your scale reads in pounds and the airline weighs in kilograms, aim for 50 lb or less and you will be under 23 kg.
Scenario 2: Body weight in stone
UK bathroom scales and medical forms often use stone and pounds. To convert:
- 11 st = 11 × 14 = 154 lb, which is 69.85 kg.
- 165 lb ÷ 14 = 11.7857 st. The decimal part is not pounds; multiply it by 14 to get 11 st 11 lb.
The same trap as feet and inches applies: 11.5 stone is 11 st 7 lb, not 11 st 5 lb.
Scenario 3: Following a recipe
US recipes use ounces and pounds; most of the world uses grams.
- 8 oz = 226.8 g, often rounded to 225 g on packaging.
- 500 g = 1.10 lb, or about 1 lb 1.6 oz.
Be careful with ounces in recipes: a fluid ounce measures volume, not weight. For liquids, cups and fluid ounces, use the Volume Converter.
Scenario 4: Shipping and vehicles in tons
"Ton" means three different things depending on where you are:
- Metric ton (tonne): 1,000 kg.
- US short ton: 2,000 lb = 907.18 kg.
- UK long ton: 2,240 lb = 1,016.05 kg.
So 1 metric ton is 1.1023 US tons, and a UK long ton is 1.016 metric tons. In international shipping, if a document just says "ton", find out which one it means.
Scenario 5: Gemstones
Diamonds and other gems are weighed in carats, where 1 ct = 0.2 g exactly. A 1.5-carat stone weighs 0.3 g. Don't confuse carats (weight) with karats (gold purity), which are unrelated despite the similar name.
What about troy ounces?
Precious metals are priced in troy ounces (about 31.1 g), which are heavier than the everyday avoirdupois ounce (about 28.35 g). The ounce in this converter is the everyday one, so it is not suitable for gold and silver prices.
How to use the Weight Converter
The Weight Converter handles all the units above:
- Type a number in Value.
- Pick the From and To units: milligrams, grams, kilograms, metric tons, ounces, pounds, stone, US tons, UK tons or carats. Use ⇄ to swap.
- Read the converted value. The table below the result shows the same amount in every unit at once, which is handy when you need both pounds and stone.
Results show up to 10 significant digits. The copy button gives you a plain number without thousands separators.
Mass or weight?
Strictly, kilograms and pounds measure mass, how much matter something contains. Weight is the force gravity puts on that mass. In everyday speech, and in this converter, "weight" means mass, which is what scales are calibrated to show.
FAQ
How do I convert pounds and ounces together, like 7 lb 4 oz?
Convert the ounces to pounds first: 4 ÷ 16 = 0.25, so 7.25 lb. Then convert 7.25 lb to kilograms, which is about 3.29 kg.
Why does my BMI calculator ask for kilograms?
The BMI formula uses kilograms and meters. The BMI Calculator also has an imperial mode that converts pounds for you.
Is a "kilo" the same as a kilogram?
Yes. In everyday speech "a kilo" means one kilogram.
Switch between kilograms, pounds, stone and more with the Weight Converter.