Stone

A stone is an imperial unit of mass equal to 14 pounds. It is still widely used in the United Kingdom and Ireland for human body weight, often written as stones and pounds, such as 11 st 4 lb.

Definition and exact value

The modern stone is exactly 14 avoirdupois pounds. Because one pound is exactly 0.45359237 kilograms, one stone is exactly 6.35029318 kilograms.

Historical stones for specific commodities varied, but the modern body-weight stone is standardized at 14 pounds.

Symbol and writing rules

The common symbol for stone is st. Unit symbols are not pluralized, so write 1 st, 11 st, or 12.5 st. In everyday British and Irish speech, the singular word stone is often used even for plural body weights.

Unit hierarchy and system context

The stone belongs to the imperial weight system and sits above the pound. It is not commonly used in the United States, where body weight is usually expressed only in pounds. In the UK and Ireland, stone remains familiar for personal weighing even when official or medical records use kilograms.

Stone vs pound, kilogram and ounce

Common uses

• Personal body weight in the United Kingdom and Ireland.
• Bathroom scales and fitness tracking displays that support st and lb.
• Health conversations where patients are more familiar with stones than kilograms.
• Historical, sporting, and cultural references involving body weight.

How stones are measured and used

Most modern scales measure mass internally and then display it in the selected unit. In stone mode, a scale may show a value such as 12 st 5 lb. To convert mixed stone and pound notation to total pounds, multiply stones by 14 and add the remaining pounds.

1. Confirm whether the scale is displaying st, lb, or kg.
2. Read the whole stones first, then the remaining pounds.
3. Convert mixed notation with: total pounds = stones x 14 + pounds.
4. Convert total pounds to kilograms if metric reporting is needed.

Precision and rounding

Personal body weight is often stated to the nearest pound within a stone, such as 11 st 4 lb. Decimal stones can be useful for calculators, but mixed stones-and-pounds notation is usually clearer for everyday readers. Convert first, then round the final result.

Conversion formulas

Stone conversion table

Common mistakes

• Assuming stone is common in the United States: US body weight is normally expressed in pounds.
• Reading mixed notation as decimals: 12 st 6 lb is not 12.6 stone; it is 174 lb.
• Forgetting the exact pound value: 1 st equals exactly 14 lb.
• Using historical commodity stones: modern body-weight stone means 14 lb.
• Rounding too early: convert with exact values first, then round the final result.

Related Xunits pages

FAQ

How many pounds are in one stone?

One stone equals exactly 14 pounds.

How many kilograms are in one stone?

One stone equals exactly 6.35029318 kilograms.

What is the symbol for stone?

The common symbol is st.

Is stone used in the United States?

Not normally. The United States usually expresses body weight in pounds.

What does 12 st 6 lb mean?

It means 12 stones plus 6 pounds. Since 12 stones equals 168 pounds, the total is 174 pounds.

Is stone a mass unit or a weight unit?

Stone is treated as a mass unit in conversion. In everyday speech, it is often used when people talk about body weight.

Reference notes

This guide uses the modern imperial stone relationship of 1 st = 14 lb and the exact international pound relationship of 1 lb = 0.45359237 kg.