Weight Conversions: Stone, Pounds, Kilograms and Grams
Quick answer: One stone is 14 pounds or 6.35 kg, one pound is 0.45359237 kg exactly (about 454 g), and one kilogram is 2.2046 lb. To turn stones into kilograms, multiply by 6.35; to turn kilograms into stones, divide by 6.35. UK food labels use grams and kilograms, while many people still weigh themselves in stones.
This section brings together weight and mass conversions for UK readers: body weight in stones and kilograms, kitchen weights in grams and ounces, and heavier loads in tonnes.
Which weight units are used in the UK?
Grams and kilograms are the official units, but stones, pounds and ounces are still widely understood. Food in shops is sold and labelled in grams and kilograms, medicines are dosed in milligrams, and GP surgeries and hospitals record body weight in kilograms. Weight limit signs on roads and bridges use tonnes.
Away from labels and forms, imperial weights are part of everyday speech. Many adults know their weight as “12 stone 6” rather than 79 kg, older recipes list ounces, and new parents often announce a birth weight such as 7 lb 8 oz even though the hospital records it in kilograms. The stone is a distinctly British unit: Americans give body weight in pounds alone, so a 12-stone person in the UK is “168 pounds” in the US.
The rules on which units traders may use are explained in the guide to the UK measurement system. For quick sums on any value, try the weight converter.
Is weight the same as mass?
In everyday UK use, “weight” means mass, measured in kilograms, grams, stones or pounds. Strictly, mass is the amount of matter in an object and weight is the force gravity exerts on it, measured in newtons. Kitchen and bathroom scales are calibrated to show mass, which is why a bag of sugar labelled 1 kg has the same mass anywhere on Earth.
The kilogram is the SI base unit of mass. Since 20 May 2019 it has been defined by fixing the value of the Planck constant, replacing the metal cylinder kept near Paris that served as the standard for more than a century. Every imperial weight is defined from the kilogram: the pound is exactly 0.45359237 kg.
How do you convert stones and pounds to kilograms?
Convert the whole weight to pounds, then multiply by 0.45359237. Multiply the stones by 14 and add the extra pounds. For 11 st 4 lb, that is 11 × 14 + 4 = 158 lb, and 158 × 0.45359237 = 71.67 kg. If you only have whole stones, multiply by 6.35029 directly: 12 stone is 76.2 kg.
| Stones | Pounds | Kilograms |
|---|---|---|
| 7 st | 98 lb | 44.45 kg |
| 8 st | 112 lb | 50.80 kg |
| 9 st | 126 lb | 57.15 kg |
| 10 st | 140 lb | 63.50 kg |
| 11 st | 154 lb | 69.85 kg |
| 12 st | 168 lb | 76.20 kg |
| 13 st | 182 lb | 82.55 kg |
| 14 st | 196 lb | 88.90 kg |
| 15 st | 210 lb | 95.25 kg |
| 16 st | 224 lb | 101.60 kg |
| 18 st | 252 lb | 114.31 kg |
| 20 st | 280 lb | 127.01 kg |
How do you convert kilograms to stones and pounds?
Divide the kilograms by 0.45359237 to get pounds, then divide by 14. The whole number is the stones, and the remainder is the extra pounds. For 80 kg: 80 ÷ 0.45359237 = 176.37 lb; 176.37 ÷ 14 = 12 remainder 8.37, so 80 kg is 12 st 8.4 lb.
| Kilograms | Pounds | Stones and pounds |
|---|---|---|
| 50 kg | 110.2 lb | 7 st 12.2 lb |
| 60 kg | 132.3 lb | 9 st 6.3 lb |
| 70 kg | 154.3 lb | 11 st 0.3 lb |
| 80 kg | 176.4 lb | 12 st 8.4 lb |
| 90 kg | 198.4 lb | 14 st 2.4 lb |
| 100 kg | 220.5 lb | 15 st 10.5 lb |
The kg to lb converter and lb to kg converter handle any value. If you track your weight for health reasons, the NHS BMI calculator works from your height and weight; speak to your GP or practice nurse if you are concerned about weight loss or gain.
How many grams are in an ounce?
One ounce is 28.35 grams, and 100 grams is 3.53 ounces. The exact figure is 28.349523125 g, because an ounce is one sixteenth of a pound. In the kitchen, rounding to 28 g or even 25 g per ounce is common in older British recipes, which is why conversion charts in cookbooks do not always agree.
| Grams | Ounces | Ounces | Grams |
|---|---|---|---|
| 25 g | 0.88 oz | 1 oz | 28.3 g |
| 50 g | 1.76 oz | 2 oz | 56.7 g |
| 100 g | 3.53 oz | 4 oz (quarter pound) | 113.4 g |
| 250 g | 8.82 oz | 8 oz (half pound) | 226.8 g |
| 500 g | 17.64 oz | 12 oz | 340.2 g |
| 1,000 g (1 kg) | 35.27 oz | 16 oz (1 lb) | 453.6 g |
Weighing ingredients for baking has its own quirks, from cup measures to butter blocks. The UK cooking measurements guide covers those, and the guide to measuring 100 g of flour without scales helps when there are no scales to hand.
What is the difference between a tonne, a ton and a hundredweight?
A metric tonne is 1,000 kg, a UK (long) ton is 1,016 kg and a US (short) ton is 907 kg. The three are close enough to be confused, which matters when you are reading a vehicle weight limit, a skip or aggregate delivery, or an older document. UK road signs and delivery notes use the metric tonne, often written with a T, as in 7.5T.
| Unit | Definition | Kilograms | Pounds |
|---|---|---|---|
| Tonne (metric ton) | 1,000 kg | 1,000 kg | 2,204.6 lb |
| Long ton (UK ton) | 2,240 lb | 1,016.05 kg | 2,240 lb |
| Short ton (US ton) | 2,000 lb | 907.18 kg | 2,000 lb |
| Hundredweight (UK) | 112 lb, or 8 stone | 50.80 kg | 112 lb |
| Troy ounce | Unit for precious metals | 31.1035 g | 0.0686 lb |
Luggage is another place where kilograms and pounds meet. Airlines set their own allowances, and these change, so check your booking, but limits are normally stated in kilograms. A 23 kg limit is 50.7 lb and a 20 kg limit is 44.1 lb, so a bag that reads 50 lb on an American-made scale is just under 23 kg.
What mistakes should you avoid when converting weights?
The most common errors involve decimal stones, fluid ounces and US recipes. Check for these before you rely on a converted figure:
- Reading decimal stones as stones and pounds. 11.5 stone is 11 st 7 lb, not 11 st 5 lb, because half a stone is 7 lb. Many calculators show decimal stones, so convert the remainder by multiplying it by 14.
- Confusing ounces with fluid ounces. An ounce measures weight; a fluid ounce measures volume. They only match for water-like liquids, and a UK fluid ounce (28.41 ml) differs from a US one (29.57 ml).
- Assuming an American weight is in stones. US sources give body weight in pounds only. 170 lb is 12 st 2 lb, or 77.1 kg.
- Using 2.2 for precise work. Multiplying kilograms by 2.2 is fine for a rough answer, but the exact factor is 2.20462. On 100 kg the shortcut is about 0.5 lb out.
Weight converters and guides in this section
New weight and mass guides appear in the list below as they are published. These tools and related guides are available now:
- Weight converter: grams, kilograms, ounces, pounds, stones and tonnes in one place.
- Kg to lb converter: for gym weights, luggage and parcels.
- Lb to kg converter: for American recipes, products and fitness plans.
- Cooking converter: cups, spoons and grams for common ingredients.
- How to measure pasta without scales: portion weights using everyday objects.
Latest weight and mass guides
- Ounces to Grams for Baking: UK Conversion Chart
- Grams to Ounces UK: Converter, Formula and Chart
- Stones and Pounds to kg Converter (UK)
- How Many Pounds in a Stone? (14 lb Explained)
- kg to Stone and Pounds: Converter and Chart
- Stone to kg Chart: 1 to 30 Stone in Kilograms
Related sections
The units of measurement guide explains how the kilogram fits into the SI system. For liquids, see volume and capacity conversions, and for weighing out ingredients, see UK cooking measurements.
Frequently asked questions
How many kilograms are in a stone?
One stone is 6.35 kilograms (6.35029318 kg exactly), because a stone is 14 pounds and each pound is 0.45359237 kg.
How many pounds are in a kilogram?
One kilogram is 2.2046 pounds. Multiply kilograms by 2.2046 to get pounds, or divide pounds by 2.2046 to get kilograms.
What is 11 stone in kg?
11 stone is 154 pounds, which is 69.85 kg. That is very close to the 70 kg figure often used as an example adult weight.
How many grams are in a pound?
One pound is 453.59 grams, usually rounded to 454 g. Half a pound is 226.8 g and a quarter of a pound is 113.4 g.
Is a UK pound the same as a US pound?
Yes. Both countries use the same pound of exactly 0.45359237 kg. The difference is that the UK also uses the stone, while the US gives body weight in pounds only.
Sources
- SI base unit: kilogram, BIPM
- National Physical Laboratory, the UK’s national measurement institute
- Weights and Measures Act 1985, Schedule 1 definitions of units, legislation.gov.uk
- Calculate your body mass index (BMI) for adults, NHS