What is stone?
A stone is a unit of mass used primarily in the United Kingdom and Ireland, equal to 14 pounds. It is mainly used to express human body weight in everyday conversation.
Real-world uses
The stone is used primarily in the UK and Ireland for expressing body weight (e.g., "I weigh 11 stone"). It appears on bathroom scales sold in Britain and is the preferred unit in British medical consultations for patient weight discussions.
History
The stone has been used in the British Isles since at least the 14th century for weighing agricultural goods. Its value varied historically (from 4 to 32 pounds depending on the commodity) before being fixed at 14 pounds by the Weights and Measures Act of 1835.
Common mistakes
Assuming a stone is used outside the British Isles—it is virtually unknown in the US, continental Europe, or most other countries. Also, forgetting that 1 stone = 14 pounds, not 10 or 12.
What is pound?
A pound is a unit of mass in imperial and US customary systems equal to 16 ounces. It is widely used in the United States for body weight, grocery shopping, and general weight measurement.
Real-world uses
Pounds are the primary unit of weight in everyday American life—used for body weight, grocery items, luggage limits, and newborn birth weights. In the UK, pounds remain common for body weight despite official metrication.
History
The pound descends from the Roman "libra pondo" (a pound by weight), which is why its abbreviation is "lb." The avoirdupois pound was standardized internationally in 1959 as exactly 0.45359237 kilograms.
Common mistakes
Confusing pounds-mass (lb) with pounds-force (lbf), which are technically different quantities. Also, assuming the pound symbol "£" relates to weight—it actually denotes British currency, though both derive from "libra."
When is this conversion used?
Body weight, grocery items, and luggage limits are commonly expressed in kilograms in most countries and pounds in the US and UK, making this one of the most frequently needed mass conversions.
Worked examples
1 stone = 14 pound
1 pound = 0.45359237 kilogram
How to convert stone to pound
To convert stone to pound, multiply the value by 14.
To convert pound back to stone, multiply by 0.07142857.
Measurement standards
The kilogram is defined by fixing the Planck constant to exactly 6.62607015 × 10⁻³⁴ joule-seconds, as established at the 26th General Conference on Weights and Measures in 2018. This ended the last SI definition based on a physical artefact.
Did you know?
The International Prototype of the Kilogram, a platinum-iridium cylinder stored near Paris since 1889, was found to have drifted by about 50 micrograms relative to its copies over a century — roughly the mass of a fingerprint.
Quick reference: stone to pound
| stone | pound |
|---|---|
| 0.1 | 1.4 |
| 0.5 | 7 |
| 1 | 14 |
| 2 | 28 |
| 5 | 70 |
| 10 | 140 |
| 25 | 350 |
| 50 | 700 |
| 100 | 1,400 |
| 250 | 3,500 |
| 500 | 7,000 |
| 1,000 | 14,000 |
Common values
| stone | pound | |
|---|---|---|
| A paperclip | 0.15747304 stone | 2.20462262 pound |
| A smartphone | 27.55778277 stone | 385.80895882 pound |
| A bag of sugar | 0.15747304 stone | 2.20462262 pound |
| Average adult human | 11.02311311 stone | 154.32358353 pound |
| A small car | 188.9676533 stone | 2,645.54714622 pound |