kg to Stone: Convert Kilograms to Stones
Convert kg to stone with the exact factor: 1 kg equals 0.1575 stone. Learn the formula, why the UK uses stones for body weight, and how to switch between the systems.
Why Kilograms to Stones Comes Up
The stone is a traditional British unit still used in the UK and Ireland for body weight, while kilograms are the global standard. Anyone comparing a UK weight chart with a metric scale needs to move between the two.
One kilogram equals about 0.1575 stone. Our kg and stone converter handles the switch in either direction, but the factor below lets you estimate by hand.
The kg to Stone Formula
One stone is defined as exactly 6.35029318 kilograms. To convert kilograms to stones, divide the kilogram value by 6.35029318.
The Exact Calculation
For 1 kg: 1 / 6.35029318 = 0.157473 stone, usually rounded to 0.1575 stone. For 10 kg: 10 / 6.35029318 = 1.57473 stone, about 1.57 st.
The division works for any weight. Because the stone is larger than the kilogram, the stone number is always smaller than the kilogram number for the same mass.
Why Divide by 6.35
The stone was standardized as 14 pounds, and the pound is defined as 0.45359237 kg, so 14 × 0.45359237 = 6.35029318 kg per stone. Dividing kilograms by that figure answers "how many stones fit into this mass."
What the Numbers Look Like
Body-weight examples make the scale concrete. 63.5 kg is exactly 10 stone. 70 kg is about 11.02 stone. 50 kg is about 7.87 stone. UK charts usually quote weight as "11 st 2 lb" style, splitting stones from leftover pounds.
If a UK friend says they weigh 12 stone, that is 12 × 6.3503 = 76.2 kg. The reverse conversion is covered in our stone to kg guide.
kg to Stone Compared With Nearby Values
A few reference points help: 5 kg = 0.787 stone, 20 kg = 3.15 stone, 100 kg = 15.75 stone. Each kilogram adds about 0.1575 stone, so the steps are small and steady.
For most adult body weights (50-100 kg), the stone figure lands between roughly 8 and 16 stone, the range UK scales commonly display.
When You Need kg in Stones
The conversion is most useful for health and fitness. A metric gym card showing 80 kg means about 12.6 stone. UK baby-weight notes, diet trackers, and medical forms often use stones, so converting keeps records consistent.
It also helps when buying equipment or following training plans written with British units.
Frequently Asked Questions
How many stone is 1 kg?
1 kg equals 0.157473 stone, normally rounded to 0.1575 stone.
How do I convert kg to stone?
Divide the kilogram value by 6.35029318. For example, 70 kg / 6.3503 = 11.02 stone.
How many kg is a stone?
One stone is exactly 6.35029318 kg, about 6.35 kg.
Why do Britons use stones for weight?
The stone is a long-standing UK unit for body weight; it equals 14 pounds and remains common on British scales and health charts.
What is 63.5 kg in stone?
63.5 kg equals exactly 10 stone, since 10 × 6.35029318 = 63.5029 kg.
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Stones to kg Converter
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Quick Summary
1 kg equals 0.1575 stone. Divide kilograms by 6.35029318 (the exact kg per stone): 1 / 6.3503 = 0.1575 st. The UK uses stones for body weight, where 63.5 kg = 10 stone.
Related Guide
Stone to kg: Convert Stones to Kilograms
Convert stone to kg with the exact factor: 1 stone equals 6.35 kg. Learn the formula, how UK body weight maps to metric, and common stone-to-kg values.
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50 kg to lbs: Convert 50 Kilograms to Pounds for Health and Shipping
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Disclaimer
Unit conversions on this site use internationally recognized, fixed conversion factors (for example, 1 inch = 2.54 cm, 1 pound = 0.45359237 kg, 1 °F = (°C × 9/5) + 32). They are provided for general, informational, and educational use. For applications where accuracy is critical — such as medical dosing, engineering, scientific research, trade, or legal compliance — always verify results against authoritative sources such as the U.S. National Institute of Standards and Technology (NIST) and the official International System of Units (SI) brochure, and follow any applicable local standards.
Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 pound (lb, avoirdupois) = 0.45359237 kilograms (exact)
- EXACT1 ounce (oz, avoirdupois) = 28.349523125 grams (exact, 1/16 lb)
- EXACT1 stone (st) = 6.35029318 kilograms (exact, 14 lb)
- EXACT1 short ton (US) = 907.18474 kilograms (exact, 2000 lb)
Common Pitfalls & How to Avoid Them
Mass vs. weight
The pound and kilogram are units of MASS, not force. On Earth, mass and "weight" read the same number in practice, but a 70 kg mass weighs less on the Moon. UnitFig converts mass; for scientific force you need newtons (1 lbf = 4.4482216152605 N, exact).
Avoirdupois vs. troy ounce
Cooking and body weight use the avoirdupois ounce (28.349523125 g). Gold and precious metals use the troy ounce (31.1034768 g). Never mix them — the error is about 10%.
Rounding the factor
Using 2.2 instead of the exact 2.20462262 overstates small errors at large values. For medical dosing or competition weight classes, keep the full factor or use a converter.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
Last Updated 2026 | This article was reviewed for accuracy