Why Does the UK Still Use Stone?
Britain went metric decades ago, yet most Britons still say "I weigh 11 stone" rather than "I weigh 70 kilos". Here is why the stone refuses to die.
The Short Answer: Culture Beats Law
The UK officially adopted the metric system starting in 1965, and metric units became compulsory for most trade by the 1980s. Yet body weight was never forced to change. No law told people to stop saying "stone", so they never did. Three generations later, the stone remains the default language of British body weight.
Surveys consistently find that around 70 percent of Britons think of their own weight in stone and pounds rather than kilograms. It is not ignorance of metric; it is identity. Asking a Briton their weight in kilos is like asking an American their height in centimetres. They could work it out, but it would not feel like their weight.
A 700-Year Habit
1389
An Act of Parliament standardises the stone for the wool trade at 14 pounds. Wool was England's most valuable export, and merchants needed a consistent measure.
1835
The Weights and Measures Act fixes the stone at exactly 14 pounds for all British trade. By now it is deeply embedded in daily life.
1965
The UK begins voluntary metrication. Industry converts, but nobody tells the public to stop weighing themselves in stone.
1995
Metric becomes compulsory for most retail trade in the UK. Loose goods must be sold in kilos. Body weight remains untouched.
Today
Bathroom scales still offer a stone setting. Newspapers report celebrity weights in stone. GPs convert stone to kg for the records, then discuss stone with the patient.
Five Reasons the Stone Survived
1. The NHS Speaks Both Languages
UK hospitals and GP surgeries officially record weight in kilograms. But clinicians know their patients think in stone, so consultations routinely involve mental translation: the nurse weighs you in kg, then tells you the stone equivalent. This bilingual habit keeps stone clinically relevant. If the NHS had insisted on kilograms-only conversations, the stone might have faded a generation ago.
2. The Media Keeps It Alive
British newspapers report weights in stone: boxers weigh in at "17 stone", reality TV contestants "lost 3 stone". Headlines written in kilograms would confuse readers, so editors stick with what the audience understands. Every headline reinforces the unit for millions of readers.
3. Scales Default to Stone
Bathroom scales sold in the UK have offered a stone/pounds setting for decades. Most people never change the default their parents used. Smart scales from brands like Withings and Renpho still include stone as a display option specifically for the UK market. See our guide on changing your scales to stone.
4. It Is a Convenient Size for Bodies
Human body weights fall in a narrow band: roughly 7 to 20 stone for most adults. That is a comfortable two-digit range. In kilograms the same band is 45 to 127, and in pounds it is 98 to 280. Stone hits a sweet spot: numbers small enough to say easily, precise enough with the leftover pounds ("11 stone 6" tells you more than "72 kg" at a glance).
5. Nobody Was Ever Forced to Stop
Metrication targeted trade, road signs, and industry. Personal body weight was private, informal, and unregulated. Without a forcing event, language simply did not change. The stone survived the way Fahrenheit survived in American weather reports: not by law, but by habit.
Will the Stone Ever Disappear?
Probably not soon. Younger Britons are more metric-literate than their grandparents, and fitness apps default to kilograms. But as long as parents teach children their weight in stone, the unit renews itself each generation. The most likely future is the current one: official kilograms, conversational stone, and a permanent need to convert between them.
Which is exactly why this site exists. Whether you think in stone, kilograms, or pounds, our converters translate instantly. Try the stone to kg converter, the kg to stone converter, or browse the full conversion chart.
Frequently Asked Questions
Why does the UK still use stone for weight?
Cultural habit is the main reason. Although the UK officially adopted the metric system, generations grew up thinking of body weight in stone and pounds. Media, bathroom scales, and everyday conversation keep it alive.
Do UK doctors use stone or kg?
UK medical professionals officially record weight in kilograms, but many still discuss weight with patients in stone and pounds because patients understand it better.
When did the UK switch to metric?
The UK began metrication in 1965 and made metric units compulsory for most trade by the 1980s. However, body weight was never forced to change, so stone survived in everyday use.
Is the stone legally recognised in the UK?
The stone is defined in UK law as exactly 6.35029318 kg, but it is not a legal unit for trade. It survives as a customary unit for personal body weight only.
Which countries use stone for weight?
The United Kingdom and Ireland are the only countries where stone is commonly used, almost exclusively for human body weight.