Convert Stone to Kilograms – Weight Converter
This converter converts a single numerical value in stones (st) to kilograms (kg). The stone is an imperial unit equal to 14 avoirdupois pounds; the kilogram is the SI base unit of mass.
The tool uses the internationally agreed exact relation between the pound and the kilogram to ensure repeatable, high-accuracy results suitable for general, medical, and engineering contexts when combined with appropriate measurement and calibration practices.
Interactive Converter
Convert between stone and kilogram with precision rounding.
Quick reference table
| Stone | Kilogram |
|---|---|
| 1 st | 6.3503 kg |
| 5 st | 31.7515 kg |
| 10 st | 63.5029 kg |
| 25 st | 158.7573 kg |
| 50 st | 317.5147 kg |
| 100 st | 635.0293 kg |
Methodology
Conversion is based on the exact definition: 1 avoirdupois pound = 0.45359237 kilograms. One stone is defined as 14 avoirdupois pounds. Therefore the stone-to-kilogram factor is derived deterministically from those definitions.
Displayed results are exact up to floating-point precision. Users should choose a display precision appropriate to their use case and follow local measurement traceability and calibration requirements for regulated applications.
For contexts that require legal-for-trade or medical accuracy, use calibrated weighing equipment and follow relevant standards and regulations cited below.
Worked examples
5 st → 5 × 6.35029318 = 31.7514659 kg (round as needed for display).
0.5 st → 0.5 × 6.35029318 = 3.17514659 kg.
Further resources
Expert Q&A
Is 1 stone exactly 6.35029318 kilograms?
Yes. Given the exact international definition of 1 avoirdupois pound = 0.45359237 kg and 1 stone = 14 pounds, the product 14 × 0.45359237 yields exactly 6.35029318 kg.
How many decimal places should I use?
Choose precision based on your application: 0–2 decimals for everyday use, 2–3 decimals for nutrition/health, and more decimals only if required by engineering calculations. For legal-for-trade or medical use, follow the precision specified by the applicable regulatory standard and the calibration certificate of the measuring device.
Does this conversion account for scale calibration or measurement error?
No. This calculator performs the mathematical unit conversion exactly. Measurement uncertainty, scale calibration, and environmental factors must be managed separately using calibrated instruments and documented traceability to national standards.
Can I convert stones and pounds combined (e.g., 11 st 4 lb)?
This converter is for a single value in stones. To convert a combined value, first convert pounds to stones (pounds ÷ 14) and add to the stone value, or convert combined mass to kilograms by converting each part and summing.
Are there regulatory requirements I should be aware of when reporting weights?
Yes. Regulated contexts such as commercial weighing, medical devices, and workplace safety require compliance with standards and local regulations. Follow equipment calibration and inspection rules from relevant authorities and standards organizations listed in the citations.
Is this suitable for engineering and scientific work?
Yes, the conversion factor is exact. For scientific and engineering work, ensure numeric precision and significant figures align with measurement uncertainty and analysis requirements.
Sources & citations
- National Institute of Standards and Technology (NIST) — https://www.nist.gov
- International Organization for Standardization (ISO) — https://www.iso.org
- Institute of Electrical and Electronics Engineers (IEEE) — https://www.ieee.org
- Occupational Safety and Health Administration (OSHA) — https://www.osha.gov