How many pounds in a stone?

Fourteen. Not ten, and not sixteen — sixteen is ounces to the pound, which is the unit below. Half a stone is therefore seven pounds rather than five, which is exactly where a decimal instinct goes wrong.

Why does the decimal stone look wrong?

Because 0.5 stone is 7 pounds rather than 5. A decimal reads as tenths and a stone divides into fourteenths, so the two never line up. That mismatch is why British scales print both numbers and why this page does too.

Is a stone still official?

It is not a legal trade unit in the UK, where goods must be sold in metric, but it remains the ordinary way a person’s weight is spoken and is what a doctor writing to a patient is likely to use. Body weight is the one place it survives.

What is the exact conversion?

One stone is fourteen pounds, and one pound is exactly 0.45359237 kilograms, so a stone is exactly 6.35029318 kg. Both figures are definitions rather than measurements, so the conversion carries no error of its own.

Stones and Pounds Converter

With weight 78 kg, stones and pounds converter comes to 12 st 4 lb — weight. It is reached in 5 steps, the last of which is total_pounds / 14, and each one is printed on the page with its numbers filled in. The formula is the one published by NIST, not an approximation fitted to it.

A body weight in kilograms as stones and pounds, the way a British scale reads it — with the remainder shown rather than folded into a decimal.

By Alex Seote, Built and maintains Rule Calculator · Formula and sources checked 16 August 2026 · How we check

Weight 78 kg

12 st 4 lb

Weight for the example below. Editing a field recomputes the calculator below; this figure holds the answer the page was loaded with.

It is written into the HTML rather than drawn by a script, so a search engine reading this page without running JavaScript still finds an answer.

WeightSwitch the unit to work backwards from stones or pounds.

Weight

12 st 4 lb

Total pounds: weight / 0.45359237171.961 lb
Total stone: total_pounds / 1412.283 st
Whole stone: floor(total_stone)12 st
Remaining pounds: (total_stone - floor(total_stone)) * 143.961 lb
Kilograms: weight78 kg

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Worked example

78 kg is 171.96 pounds, which is 12.283 stone — and a British scale reads 12 st 4 lb. The stone is fourteen pounds, not ten, so the 0.283 left over becomes 4 pounds rather than the 2.8 a decimal instinct suggests.

How to work it out yourself

1.Enter the weight in kilograms, or switch the unit to go the other way from stones or pounds.
2.Convert to pounds first, then divide by fourteen: the whole number is the stone and the remainder is the pounds. Dividing by ten instead is the mistake that makes people distrust the answer.
3.The stone is used for body weight in Britain and Ireland and almost nowhere else — a US scale gives pounds alone and a metric one kilograms.

Kilograms to stones and pounds

Weight (kg)	Weight
50	7 st 12.2 lb
55	8 st 9.3 lb
60	9 st 6.3 lb
65	10 st 3.3 lb
70	11 st 0.3 lb
75	11 st 11.3 lb
80	12 st 8.4 lb
85	13 st 5.4 lb
90	14 st 2.4 lb
95	14 st 13.4 lb
100	15 st 10.5 lb
110	17 st 4.5 lb

Every five kilograms across the usual adult range. A stone is 6.35 kg, so each step of five is a little under a stone.

The formula

Total poundsweight / 0.45359237
Total stonetotal_pounds / 14
Whole stonefloor(total_stone)
Remaining pounds(total_stone - floor(total_stone)) * 14
Kilogramsweight

Source: NIST — the pound is exactly 0.45359237 kg, BIPM — International System of Units

Questions people actually ask

How many pounds in a stone?: Fourteen. Not ten, and not sixteen — sixteen is ounces to the pound, which is the unit below. Half a stone is therefore seven pounds rather than five, which is exactly where a decimal instinct goes wrong.
Why does the decimal stone look wrong?: Because 0.5 stone is 7 pounds rather than 5. A decimal reads as tenths and a stone divides into fourteenths, so the two never line up. That mismatch is why British scales print both numbers and why this page does too.
Is a stone still official?: It is not a legal trade unit in the UK, where goods must be sold in metric, but it remains the ordinary way a person’s weight is spoken and is what a doctor writing to a patient is likely to use. Body weight is the one place it survives.
What is the exact conversion?: One stone is fourteen pounds, and one pound is exactly 0.45359237 kilograms, so a stone is exactly 6.35029318 kg. Both figures are definitions rather than measurements, so the conversion carries no error of its own.

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