What Is a Stone in Weight and How to Convert It
If you have ever read a British novel, watched a UK weight loss programme, or tried to interpret a medical record from Ireland, you have probably come across the stone as a unit of weight.
It is used almost exclusively in the UK and Ireland, and almost exclusively for body weight. Almost nobody outside those two countries grows up with it, which makes it genuinely confusing the first time you encounter it.
This article explains exactly what a stone is, how to convert it to kilograms and pounds, and provides a reference table that covers the full range of common adult body weights.
For quick conversions, the Weight Converter handles stones, kilograms, and pounds in one place.
What Is a Stone?
One stone equals exactly 14 pounds, or approximately 6.35 kilograms.
The stone has been used in Britain as a unit of weight for centuries, with various definitions depending on what was being weighed — wool, meat, and other commodities all had their own "stone" of different sizes. The 14-pound stone was standardised for body weight and trade goods, and that is the only definition still in use today.
In the UK and Ireland, body weight is typically expressed as a combination of stones and pounds — for example, "11 stone 4 pounds" rather than "158 pounds" or "71.7 kg." This combined format is written as "11 st 4 lb" or sometimes just "11 st 4."
The Conversion Formulas
Stones to kilograms:
kilograms = stones × 6.35029
Example: 11 stone = 11 × 6.35029 = 69.85 kg
Stones to pounds:
pounds = stones × 14
Example: 11 stone = 11 × 14 = 154 pounds
Kilograms to stones:
stones = kilograms ÷ 6.35029
Example: 75 kg ÷ 6.35029 = 11.81 stone = 11 stone 11 lb (0.81 × 14 = 11.3, round to 11)
Pounds to stones:
stones = pounds ÷ 14
Example: 168 lb ÷ 14 = 12 stone exactly
Converting stone + pounds combination to kilograms:
kg = (stones × 14 + pounds) × 0.453592
Example: 10 stone 8 lb = ((10 × 14) + 8) × 0.453592 = 148 × 0.453592 = 67.13 kg
Body Weight Reference Table
| Stones | Pounds | Kilograms |
|---|---|---|
| 7 st 0 lb | 98 lb | 44.5 kg |
| 7 st 7 lb | 105 lb | 47.6 kg |
| 8 st 0 lb | 112 lb | 50.8 kg |
| 8 st 7 lb | 119 lb | 54.0 kg |
| 9 st 0 lb | 126 lb | 57.2 kg |
| 9 st 7 lb | 133 lb | 60.3 kg |
| 10 st 0 lb | 140 lb | 63.5 kg |
| 10 st 7 lb | 147 lb | 66.7 kg |
| 11 st 0 lb | 154 lb | 69.9 kg |
| 11 st 7 lb | 161 lb | 73.0 kg |
| 12 st 0 lb | 168 lb | 76.2 kg |
| 12 st 7 lb | 175 lb | 79.4 kg |
| 13 st 0 lb | 182 lb | 82.6 kg |
| 13 st 7 lb | 189 lb | 85.7 kg |
| 14 st 0 lb | 196 lb | 88.9 kg |
| 14 st 7 lb | 203 lb | 92.1 kg |
| 15 st 0 lb | 210 lb | 95.3 kg |
| 15 st 7 lb | 217 lb | 98.4 kg |
| 16 st 0 lb | 224 lb | 101.6 kg |
| 17 st 0 lb | 238 lb | 108.0 kg |
| 18 st 0 lb | 252 lb | 114.3 kg |
| 20 st 0 lb | 280 lb | 127.0 kg |
Where Is the Stone Used?
The stone is used almost exclusively in two countries:
United Kingdom: Body weight in the UK is routinely discussed in stones and pounds. Doctors, nurses, pharmacists, and the general public all use it. NHS medical records often record weight in kilograms for clinical purposes, but patients typically know their weight in stone. Bathroom scales sold in the UK usually show all three units — stone, kg, and lb — switchable with a button.
Ireland: Same situation as the UK. Stones and pounds are the everyday language for body weight. Kilograms are used in clinical settings.
Outside these two countries, the stone is rarely used. Australia, New Zealand, and Canada — all former British territories — largely abandoned it during metrication in the 1970s and 1980s and now use kilograms. The US never used it.
If you are visiting the UK and someone tells you they weigh "13 stone 5," that is 187 pounds or 84.8 kg — a helpful reference frame once you have the conversion in mind.
A Practical Mental Shortcut
The stone is awkward to work with mentally unless you have a few reference points memorised.
Useful anchors:
- 10 stone = 63.5 kg = 140 lb
- 11 stone = 69.9 kg ≈ 70 kg = 154 lb
- 12 stone = 76.2 kg = 168 lb
- 14 stone = 88.9 kg ≈ 89 kg = 196 lb
From any of those anchors, each additional stone adds 6.35 kg or 14 lb, and each additional pound adds 0.45 kg.
So "12 stone 7" is 12 stone (76.2 kg) + 7 pounds (3.2 kg) = 79.4 kg, or 175 lb.
Why Only Body Weight?
The stone is used almost exclusively for human body weight in modern UK usage. You would not buy 3 stone of potatoes at a market — you would buy 19 kilograms or maybe 42 pounds, depending on the vendor.
Historically, the stone was used for various commodities, each with its own stone size. Wool was weighed in 14-pound stones; cheese in 16-pound stones; meat in 8-pound stones. These commodity-specific stone sizes all became obsolete after metrication, and only the 14-pound body weight stone survived in common use.
This survival is largely cultural rather than practical. The metric system is perfectly capable of expressing body weight, and the NHS uses kilograms in clinical records. But people know their weight in stone the way they know their height in feet and inches — it is the unit they grew up with, and changing that habit is slow.
Stone vs Kilograms on the Scales
If you buy a body weight scale in the UK, it will almost certainly have a unit toggle. The display cycling through "st lb / kg / lb" is standard on UK bathroom scales.
If you are recording weight for medical, fitness, or dietary tracking purposes, kilograms are usually cleaner to work with — they are what clinical charts, BMI calculators, and nutrition apps use natively. The Weight Converter makes it easy to translate a stone reading into kilograms for any of those purposes.
