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Kilograms to stone

Multiply kilograms by 0.157473 to get stone.

1 kg = 0.157473 stBIPM SI · UK W&M Act 1985
kg
12.5978st

80 kg = 12.5978 st

How to convert kilograms to stone

The stone is exactly 14 pounds — the imperial unit defined in Schedule 1 of the UK Weights and Measures Act 1985, so 1 st = 6.35029318 kg exactly. The kilogram is the SI base unit of mass, fixed since 2019 by defining the Planck constant as exactly 6.62607015×10⁻³⁴ J·s.

Worked example — 80 kg: 80 × 0.157473 = 12.5978 st. (12 st 8.4 lb)

Kilograms to stone table

Common conversions. The reverse table is on stone to kilograms.
KilogramsStoneStone and lb
50 kg7.8737 st7 st 12.2 lb
60 kg9.4484 st9 st 6.3 lb
70 kg11.0231 st11 st 0.3 lb
75 kg11.8105 st11 st 11.3 lb
80 kg12.5978 st12 st 8.4 lb
90 kg14.1726 st14 st 2.4 lb
100 kg15.7473 st15 st 10.5 lb
110 kg17.322 st17 st 4.5 lb
120 kg18.8968 st18 st 12.6 lb

Reverse and related

About kilograms and stone

Kilogram (kg)

1 kg = 0.157473 st

Definition. The SI base unit of mass, fixed since 2019 by defining the Planck constant as exactly 6.62607015×10⁻³⁴ J·s

History and origin

The kilogram began in 1795 as the mass of one litre of water at the melting point of ice, and from 1889 was embodied in a platinum-iridium cylinder kept near Paris, the International Prototype Kilogram. In 2019 the SI retired that physical artefact and redefined the unit through a fixed value of the Planck constant, leaving its size unchanged.

Current use

It is the base unit of mass almost everywhere on Earth. The main everyday exception is the United States, where people weigh in pounds even though US science, medicine and industry work in kilograms.

Source: BIPM, The International System of Units (SI), 9th ed. (2019)

Stone (st)

1 st = 6.3503 kg

Definition. Exactly 14 pounds — the imperial unit defined in Schedule 1 of the UK Weights and Measures Act 1985, so 1 st = 6.35029318 kg exactly

History and origin

The stone was a trading weight that varied by commodity and region across medieval Europe before Britain fixed it at 14 pounds. It is defined in Schedule 1 of the UK Weights and Measures Act 1985.

Current use

The stone is still the usual way to give body weight in the United Kingdom and Ireland, where a person might be eleven stone four, but it is little used elsewhere.

Source: Weights and Measures Act 1985 (UK), Schedule 1, Part VI

Where people use this

Kilograms: body weight outside the US, groceries and produce, checked-luggage limits. Stone: body weight in the UK and Ireland. 70 kg is about 11 st 0 lb.

How we know this is right
The factor is fixed by the standards that define the units, not chosen — so it is exact, not a measurement:
1 st = 6.35029318 kg, so 1 kg = 1 ÷ 6.35029318 = 0.157473 st.

Every value is carried to full double precision; the display is rounded.

Sources: Weights and Measures Act 1985 (UK), Schedule 1, Part VI; BIPM, The International System of Units (SI), 9th ed. (2019).

Questions people ask

How many stone is 70 kg?

70 kg is about 11 stone 0 lb (11.02 stone). To convert kg to stone, multiply by 0.1575.

What is 80 kg in stone?

80 kg is about 12 st 8 lb (12.6 stone), and 90 kg is about 14 st 2 lb.

How do you convert kg to stone?

Multiply the kilograms by 0.1575, or divide by 6.35. A 60 kg person is about 9 st 6 lb.

All kilogram conversions