Stones to Pounds Converter

The stone goes back to Anglo-Saxon and medieval European trade, where merchants used literal stones of standardized weight at market scales. Local stones varied wildly by region and by commodity (wool, cheese, meat, hemp), with values from about 5 to 24 pounds. The UK 1835 Weights and Measures Act finally fixed the stone at exactly 14 pounds for all goods, replacing the patchwork of local definitions.

Stones and pounds remain common for personal body weight in everyday conversation in the UK and Ireland. Medical records and medication calculations generally use kilograms, even when a scale also shows stones. The US commonly uses pounds, while most other countries use kilograms.

The 14 pound stone is the legacy of dozens of older regional stones that gradually converged. Wool stones, cheese stones, meat stones, and butcher's stones each had different values, but the wool stone of 14 pounds dominated long-distance trade in late medieval England. The 1835 act simply made that figure the only legal stone, and 14 has stayed the definition ever since.

One stone equals exactly 6.35029318 kg, derived from 14 pounds times the international pound (0.45359237 kg). For mental math, treat a stone as about 6.35 kg. So 10 stones is about 63.5 kg, and 12 stones is about 76.2 kg.

Stone-and-pound notation lists the whole stones first, then the leftover pounds (always under 14). 11 st 4 lb means 11 times 14 plus 4 equals 158 pounds, which is 71.7 kg. The converter accepts that combined form directly, or you can enter pounds or kilograms and read back the equivalent stones-and-pounds.