1 Stone to kg
Exactly how many kilograms are in 1 stone? 1 st = 6.35029 kg, with a quick reference table for other common stone values.
1 Stone to kg: The Quick Answer
1 stone (1 st) converts to 6.35 kg. Whether you are reading a metric label, a recipe, or an international spec, knowing how to convert 1 stone (1 st) keeps your numbers consistent. Use our stones to kg converter for any value, or read on for the full breakdown of the 6.35 kg result.
The Exact Stones to Kilograms Formula
The stone is a British unit equal to exactly 14 pounds, and 1 pound is 0.45359237 kg, so 1 stone = 6.35029318 kg. To convert stones to kilograms, multiply the stones by 6.3503.
Step-by-Step Calculation
Start with 1 st. Multiply by 6.3503: 1 x 6.3503 = 6.3503 kg, which rounds to 6.35 kg.
A Quick Mental Estimate
A stone is a bit over 6 kg (6.35 kg), so you can think of 1 st as roughly 6.3 kg.
Where 1 stone (1 st) Comes Up
The stone is still used in the UK and Ireland for body weight, so a "12 stone" adult or a gym target in stones needs a kilogram figure for metric records or international forms. One stone is 6.35 kg.
1 stone (1 st) Compared With Nearby Values
Nearby stone amounts: 2 st = 12.7 kg, 5 st = 31.75 kg.
On the other side, 10 st = 63.5 kg, 12 st = 76.2 kg. Each step moves the figure smoothly, so the same formula scales to any amount.
Practical Uses of the 1 stone (1 st) Conversion
Use this when a British weight is given in stones and you need kilograms for a metric scale or form. Our stones to kg converter converts any amount, and kg to lbs links kilograms to pounds.
Frequently Asked Questions
How many kg is 1 stone?
1 st = 6.35029 kg.
How many kg is 10 stone?
10 st × 6.35029 = 63.503 kg.
How many pounds are in a stone?
1 stone = 14 lb = 6.35029 kg.
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Quick Summary
1 stone (1 st) equals 6.35 kg. Use the stones to kilograms relationship shown above for exact, repeatable results.
Related Guide
Stones to Pounds: Convert UK Stone Weight to US Pounds
Convert stones to pounds with the exact factor. 1 stone equals 14 lbs. See the math, UK fitness context, and a quick reference table.
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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