Convert Kilograms to Stone – Weight Converter
This converter transforms a mass value in kilograms (kg) into stones (st) using the internationally defined fixed relationship between the metric kilogram and the avoirdupois pound. It is intended for quick reference, personal weight conversion, and non-critical engineering or reporting tasks.
The conversion is arithmetic and exact given the defined constant; however practical measurement uncertainty depends on the instrument, calibration state, and rounding. Guidance on calibration and traceability to national standards is provided below.
Interactive Converter
Convert between kilogram and stone with precision rounding.
Quick reference table
| Kilogram | Stone |
|---|---|
| 1 kg | 0.1575 st |
| 5 kg | 0.7874 st |
| 10 kg | 1.5747 st |
| 25 kg | 3.9368 st |
| 50 kg | 7.8737 st |
| 100 kg | 15.7473 st |
Methodology
The tool uses the internationally agreed definitions: one avoirdupois pound is exactly 0.45359237 kilograms, and one stone is defined as 14 avoirdupois pounds. Multiplying those gives 1 stone = 6.35029318 kilograms.
Because the relationship is a fixed mathematical constant, the converter applies a single division or multiplication operation. Displayed results are rounded for readability; users should retain additional significant digits when preparing scientific or regulatory reports.
For contexts where measurement accuracy matters (medical dosing, lab records, trade, or legal-for-trade weighing), ensure instruments are calibrated and traceable to national standards as described in the cited standards and guidance.
Worked examples
70 kg ≈ 70 ÷ 6.35029318 = 11.0231 st → displayed as 11.02 st (equivalently about 11 st and 0.32 lb).
80 kg ≈ 12.5984 st → displayed as 12.60 st.
50 kg ≈ 7.8731 st → displayed as 7.87 st.
Expert Q&A
Is the conversion exact?
Yes. The arithmetic conversion uses exact international definitions (1 lb = 0.45359237 kg and 1 st = 14 lb) so the factor 6.35029318 kg per stone is exact by definition. Any inaccuracy in a reported value comes from measurement error, rounding, or display precision.
Why do results sometimes show small differences from other converters?
Differences usually come from display rounding, how many decimal places are shown, or whether a service converts to 'stones and pounds' and rounds pounds. The underlying constant is the same; adjust displayed precision if you need more significant figures.
How do I convert to stones and pounds (mixed units)?
First compute total stones = kilograms ÷ 6.35029318. Take the integer part for whole stones. Multiply the fractional part by 14 to get pounds; round pounds to the desired precision (for example, nearest 0.1 lb).
When should I be concerned about calibration and standards?
For trade, clinical, or regulatory uses, measurement devices must be calibrated and traceable to national standards. Follow applicable national and international guidance on calibration intervals, tolerances, and uncertainty reporting cited in the references.
Sources & citations
- National Institute of Standards and Technology (NIST) - Weights and Measures — https://www.nist.gov/pml/weights-and-measures
- International Organization for Standardization (ISO) — https://www.iso.org
- IEEE Standards Association (floating-point representation guidance) — https://www.ieee.org
- Occupational Safety and Health Administration (OSHA) — https://www.osha.gov