Article — Pounds to Stone Converter
Pounds to Stone Converter: The 14-Pound Rule
One stone equals exactly 14 pounds, which equals 6.35029 kilograms. Divide pounds by 14 to get stone; multiply stone by 14 to go back. UK speakers split the result into whole stone plus loose pounds — 154 lb is 11 st 0 lb, 150 lb is 10 st 10 lb. The 14-pound stone has been the UK statutory standard since the Weights and Measures Act of 1835.
The stone survives almost nowhere else. Americans weigh in pounds; continental Europeans weigh in kilograms; only the UK and Ireland hold on to the old wool-trader unit for adult body weight. Bathroom scales sold in Britain still show stone-and-pounds alongside kilograms, and the NHS records body weight in both.
What is the pounds to stone conversion?
The pounds to stone conversion translates a weight measured in avoirdupois pounds into the UK customary unit of stone. The stone is purely a mass unit — not a measure of force or volume — and is used almost exclusively for human body weight. Conversion is integer arithmetic: 14 pounds make one stone.
Unlike many imperial-to-metric conversions, the pounds-to-stone factor has no measurement uncertainty. The UK Parliament fixed it by statute. Earlier centuries used regional stones of 8, 12, 14, 16, and 24 pounds depending on the commodity, but the 1835 Act standardised the trade stone at 14 pounds for the whole kingdom.
Before 1835, the “wool stone” was 14 lb, the “meat stone” was 8 lb, and the “glass stone” was 5 lb. Buying cheese in one town and selling it in another could change your stone count without changing the cheese. Parliament picked the wool stone — the most-used — as the legal standard.
The pounds to stone formula
The arithmetic is one division.
stone = pounds ÷ 14 pounds = stone × 141 stone = 14 lb 1 stone = 6.35029 kg10 st = 140 lb 14 st = 196 lbUK form: floor(lb/14) st + (lb mod 14) lbThe UK speech form rounds down to whole stone and reports the remainder as loose pounds. 175 lb is 12 stone 7 (because 175 = 12 × 14 + 7). 200 lb is 14 stone 4. Decimal stone is rare in British usage and tends to mark the speaker as not British.
Why one stone is 14 pounds
Historically arbitrary. The English crown taxed wool exports throughout the medieval period and needed a standard weight for bales. The royal commission that fixed the wool stone landed on 14 pounds. The 1389 Statute of Richard II reaffirmed the value, the Tudor weights commissions reaffirmed it again, and the 1835 Act made it the only legal stone in trade.
There is no underlying physical or geometric reason for the number 14. It is the historical accumulation of practice frozen into law. The same legal accident gave us 12 inches in a foot, 16 ounces in a pound, and 8 stone in a hundredweight — tidy ratios that someone, somewhere, decided to enforce.
Pounds to stone reference table
The values UK speakers actually use, spelled out:
- 98 lb = 7 st 0 lb (44.45 kg)
- 112 lb = 8 st 0 lb (50.80 kg)
- 126 lb = 9 st 0 lb (57.15 kg)
- 140 lb = 10 st 0 lb (63.50 kg)
- 147 lb = 10 st 7 lb (66.68 kg)
- 154 lb = 11 st 0 lb (69.85 kg)
- 168 lb = 12 st 0 lb (76.20 kg)
- 175 lb = 12 st 7 lb (79.38 kg)
- 182 lb = 13 st 0 lb (82.55 kg)
- 196 lb = 14 st 0 lb (88.90 kg)
- 210 lb = 15 st 0 lb (95.25 kg)
- 224 lb = 16 st 0 lb (101.60 kg)
How to read the UK st-and-lb format
British conversational form drops decimals and ranges. “Eleven stone seven” means 11 st 7 lb, which is 161 lb (73.0 kg). “Ten ten” means 10 st 10 lb, or 150 lb. Older speakers often say “he weighs ten stone” without the pound count, treating sub-stone precision as imprecise enough to ignore.
The plural of stone, when used as a unit of body weight, is “stone” with no s. “He weighs fourteen stone” is correct; “he weighs fourteen stones” sounds wrong to British ears, the same way “ten foot” is correct for measurement but “ten foots” would be ungrammatical. The s appears only when referring to the literal rocks.
Stone in the UK vs the US
The stone is essentially a UK-and-Ireland phenomenon. American doctors, gyms, and consumer products use pounds; American newspapers report celebrity weights in pounds; and an American who says “I weigh eleven stone” will receive blank looks. The 1894 Mendenhall Order in the US tied the US pound to the metric kilogram but never adopted the stone.
British sport keeps stone alive in two niches: amateur boxing weight classes and horse-racing jockey weights. A jockey weighed in at 8 st 7 lb (119 lb) carries that figure throughout the meeting, and exceeding it by even half a pound triggers a steward inquiry.
Common pounds to stone mistakes
Converting 150 lb to “10.7 stone” and rounding to “11 stone” loses information that matters in everyday UK speech. The correct UK answer is 10 st 10 lb — the precise integer mass. 11 st 0 lb is 154 lb, four pounds heavier. The difference matters in medicine, sports, and dosing.
The second mistake is forgetting that stone is plural without an s. Writing “14 stones” on a medical form will get the form rejected for non-standard wording. Use “14 stone” or convert to kilograms.
The third pitfall: assuming the stone is the same as a hundredweight or a quarter. It is not. One hundredweight (cwt) is 8 stone (112 lb in UK long cwt). One quarter is 2 stone (28 lb). These units share the same family but are distinct.
Stone to kilograms conversion
The chain runs stone → pounds → kilograms. One stone is 14 pounds; one pound is exactly 0.45359237 kilograms by the 1959 International Yard and Pound Agreement. So one stone is 14 × 0.45359237 = 6.35029318 kg, exact.
- 1 stone = 6.35029 kg
- 10 stone = 63.50 kg
- 11 stone = 69.85 kg
- 12 stone = 76.20 kg
- 14 stone = 88.90 kg
- 15 stone = 95.25 kg
A UK adult of average weight (about 11 stone 7) is 161 pounds or 73 kg. The NHS uses 6.35 kg/st as a working factor in its body-weight conversion tables, accepting the 0.00029 kg rounding loss in clinical practice.