Stones to kg Converter
Convert British stones to kilograms for international weight comparison and fitness tracking.
How It Works
Formula: st to kg = value × 6.35029318
Example: 10 st = 63.502932 kg
Note: 1 stone equals 6.3503 kilograms (14 lbs), a British unit still used for body weight in the UK and Ireland.
Common Uses
Quick Conversion Table
| st | kg |
|---|---|
| 1 | 6.3503 |
| 5 | 31.7515 |
| 10 | 63.5029 |
| 25 | 158.7573 |
| 50 | 317.5147 |
| 100 | 635.0293 |
| 150 | 952.544 |
| 200 | 1270 |
Rounding Rule
Rounded to 4 decimal places
Error Margin
±0.0001 kg
Precision Guidance
For weight comparison, round to 1 decimal place. For records, keep 2-4 decimals.
Common Mistakes
A stone is 14 lbs, not 16. Do not confuse it with a US quarter (25 lbs).
Frequently Asked Questions
What is 1 stone in kg?
1 stone equals 6.3503 kilograms (1 st = 14 lbs = 6.35029318 kg).
How many pounds is a stone?
1 stone equals 14 pounds. This converter first relates stones to the avoirdupois pound, then to kilograms.
Why do Americans need stones?
British and Irish weight is often given in stones; this converter helps Americans understand those figures.
How do I convert 10 stone to kg?
Multiply 10 by 6.3503. The result is 63.503 kg.
Deep Dive 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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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 converter was reviewed for accuracy