What Is stone (UK)?
The stone UK is a unit of weight. People in the United Kingdom and Ireland often use it to say how heavy a person or animal is. For example, someone might say “I weigh 9 stone” instead of using only kilograms or pounds.
Definition
The stone UK is defined using the pound. One stone is equal to 14 pounds.
In the metric system, one stone is exactly 6.35029318 kilograms. In everyday use, people usually round this and say 1 stone is about 6.35 kilograms.
So you can remember:
- 1 stone = 14 pounds
- 1 stone is about 6.35 kilograms
History / Origin
The idea of using a stone as a weight goes back many hundreds of years. Long ago, people used real stones as simple weights in markets when they bought and sold goods. Different places had different sized stones, so the weight was not always the same.
In medieval England, traders used stones to measure things like wool, cheese, and other goods. Over time, the value of the stone became more fixed. By the 19th century in the United Kingdom, the stone was set by law to be 14 pounds. This made trade and measuring more fair and consistent.
Even after the metric system became common in science and trade, many people in the UK and Ireland kept using the stone in daily life, especially for body weight.
Symbol & Abbreviation
The standard symbol for the stone UK is:
- st
Examples of how it is written:
- 9 st (means 9 stone)
- 11 st 4 lb (means 11 stone and 4 pounds)
Notice that pounds are usually written as lb, so a weight can be written using both stone and pounds together.
Current Use Around the World
The stone UK is not a main unit in most countries. However, it is still used in some places, mainly for body weight.
- United Kingdom People often give their body weight in stone and pounds, like 10 st 6 lb.
- Ireland Many people also use stone for body weight in daily conversation.
- Other countries In most other places, people use kilograms or pounds. The stone is known but rarely used.
In sports such as boxing, horse racing, and sometimes rugby in the UK, weights are often written in stone and pounds. In official science, medicine, and international trade, the metric system is preferred, so kilograms are used instead of stone.
Example Conversions
Here are some simple conversions between stone, pounds, and kilograms. Rounded values are used to make them easy to remember.
- 1 st = 14 lb ≈ 6.35 kg
- 2 st = 28 lb ≈ 12.7 kg
- 5 st = 70 lb ≈ 31.75 kg
- 8 st = 112 lb ≈ 50.8 kg
- 10 st = 140 lb ≈ 63.5 kg
- 12 st = 168 lb ≈ 76.2 kg
- 14 st = 196 lb ≈ 88.9 kg
- 16 st = 224 lb ≈ 101.6 kg
To convert from stone to pounds:
- Multiply the number of stone by 14.
Example 1
7 st in pounds
- 7 × 14 = 98 lb
To convert from stone to kilograms:
- Multiply the number of stone by about 6.35.
Example 2
9 st in kilograms
- 9 × 6.35 ≈ 57.15 kg
To go from kilograms to stone, divide the kilograms by 6.35.
Example 3
70 kg in stone
- 70 ÷ 6.35 ≈ 11.0 st
Related Units
The stone UK is closely related to other units of mass or weight.
- Pound (lb) The base unit for the stone in the UK system. 1 st = 14 lb.
- Ounce (oz) A smaller unit. 1 lb = 16 oz, so 1 st = 224 oz.
- Kilogram (kg) The main unit in the metric system. 1 st ≈ 6.35 kg.
- Gram (g) A small metric unit. 1 kg = 1000 g, so 1 st ≈ 6350 g.
- Hundredweight (cwt) A larger UK unit. 1 UK hundredweight = 112 lb = 8 st.
- Tonne (t) A metric ton equal to 1000 kg. 1 t ≈ 157.47 st.
FAQs
What is a stone in weight?
A stone is a unit of weight used mainly in the UK and Ireland. One stone equals 14 pounds, which is about 6.35 kilograms.
Why is it called a stone?
Long ago, people used real stones as simple weights in markets. Over time, the word “stone” stayed as the name for this fixed unit of weight.
Is the stone part of the metric system?
No. The stone is part of the old imperial or customary system. The metric system uses units like grams and kilograms instead.
Where is the stone still used today?
The stone is still common in the United Kingdom and Ireland when talking about body weight and in some sports. In most other countries, people use kilograms or pounds.
How do I quickly convert stone to kilograms?
To get a quick answer, multiply the number of stone by 6.35. For example, 10 st × 6.35 ≈ 63.5 kg.
How do I convert stone and pounds together?
First turn everything into pounds. Multiply the stone by 14 and then add the extra pounds. After that, you can convert pounds to kilograms if you need to.
Is the stone an official unit?
The stone is not an SI unit and is not used in most official scientific work. However, in the UK it is still recognized for body weight and appears in some medical and sports contexts.