The History of the Stone Unit
The stone (symbol: st) is an English and imperial unit of mass equal to precisely 14 pounds (lbs), or 6.35029318 kilograms.
Where Did the Stone Come From?
Historically, trading communities evaluated agricultural goods using physical native stones. Because a physical rock could vary widely depending on the region, the official weight of a "stone" shifted enormously across European countries ranging anywhere from 3 kg to over 15 kg depending on the city.
It wasn't until the Weights and Measures Act of 1835 that the British Crown formally standardized the stone for trade to exactly 14 pounds (lbs).
Countries That Still Use It
Today, the stone is almost exclusively used formally and informally in the United Kingdom and Ireland. While the UK legally adopted the metric system and officially measures medical weight in kilograms, civilian culture continues to instinctively express human body mass in stones and pounds.
The United States, having split off before the 1835 standardization, relies almost entirely on pounds and overlooks the stone entirely in modern vocabulary.
Stone vs Kilogram
- 1 Stone = 6.35029 kg
- 1 Kilogram = 0.15747 st
- 1 Stone = 14 Pounds
Frequently Asked Questions
What is a stone?
A stone is a unit of weight in the imperial system equal to exactly 14 pounds or 6.35029 kilograms.
Who still uses the stone measurement?
The stone is primarily used in the United Kingdom and Ireland today for informally expressing human body weight.
Why doesn't America use the stone?
The US customary system adopted the pound (lb) as the primary weight unit before the stone became formally standardized for trade in Britain in 1835.