Convert Kilograms to Stone

The formula

To convert kilograms to stone, divide the kg value by the number of kilograms in one stone:

st = kg ÷ 6.35029

• st — the result in stone.
• kg — the input weight in kilograms.
• 6.35029 — the number of kilograms per stone (= 14 lb × 0.45359237 kg/lb, exactly 6.35029318 kg).

To express the result in stone and pounds, take the decimal part and multiply by 14. For example, 11.65 st = 11 st and (0.65 × 14) ≈ 9 lb.

Worked example

Using the calculator’s default input of 74 kg:

1. Take the kg value: 74.
2. Divide by 6.35029: 74 ÷ 6.35029 = 11.653...
3. Whole part = 11 stone; decimal 0.653 × 14 ≈ 9.1 lb.

So 74 kg ≈ 11 stone 9 lb (or 11.65 stone).

Conversion table

Common kilogram values converted to stone:

Kilograms (kg)	Stone (st)
45	7.09
50	7.87
55	8.66
60	9.45
65	10.24
70	11.02
74	11.65
75	11.81
80	12.60
85	13.39
90	14.17
95	14.96
100	15.75

History & standards

The stone is an old English unit of mass equal to 14 avoirdupois pounds. It appears in records from the 14th century and was used across Britain and Ireland for trade in wool, livestock and body weight. Because the stone equals a whole number of pounds (14), it remains intuitive for people who are also familiar with pounds.

The stone was officially abolished as a legal unit of trade in the UK by the Weights and Measures Act 1985, but it persists strongly in everyday British and Irish conversation for body weight. Its metric equivalent is fixed by the 1959 International Yard and Pound Agreement: 1 stone = 14 × 0.45359237 kg = 6.35029318 kg exactly.

The kilogram has been the SI base unit of mass since the metre was introduced, and since 2019 is defined by fixing the Planck constant rather than by a physical prototype.

Common applications

• Body weight in the UK and Ireland. Doctors, pharmacists and patients in Britain routinely state weight in stone and pounds; metric health records need converting for these conversations.
• Weight-loss tracking. UK and Irish fitness apps often display progress in stone; gym-goers weigh themselves in kg on metric scales and convert.
• Sports. UK boxing weight categories (e.g. heavyweight >14 st 4 lb) are expressed in stone and pounds; athletes training with metric equipment need to convert.
• Comparing international data. Health and BMI studies from the UK cite stone; those from Europe cite kg — converting lets you compare like for like.

Reverse conversion

To convert stone back to kilograms, multiply by 6.35029: kg = st × 6.35029 — or use our stone to kg calculator.

Limitations & gotchas

• Stone is not used in the US. American audiences will not recognise stone as a weight unit; use pounds or kg instead when communicating across the Atlantic.
• Decimal stone vs stone and pounds. 11.65 stone is not the same as 11 stone 65 pounds. The decimal part must be multiplied by 14 to get the pounds component.
• Rounding. 6.35029318 is the exact value; using 6.35 introduces an error of <0.005% — imperceptible for body weight but worth noting for precise applications.

Sources & references

• NIST SP 811 — Guide for the Use of the International System of Units (SI).
• BIPM — The International System of Units (SI), 9th edition (2019).
• 1959 International Yard and Pound Agreement (fixing 1 lb = 0.45359237 kg exactly; therefore 1 stone = 6.35029318 kg).