stone (st)
1 stone = 6.35029318 kilograms
What is stone?
A stone is a unit of mass used primarily in the United Kingdom and Ireland, equal to 14 pounds. It is mainly used to express human body weight in everyday conversation.
Notes: Imperial unit
Real-world uses
The stone is used primarily in the UK and Ireland for expressing body weight (e.g., "I weigh 11 stone"). It appears on bathroom scales sold in Britain and is the preferred unit in British medical consultations for patient weight discussions.
History
The stone has been used in the British Isles since at least the 14th century for weighing agricultural goods. Its value varied historically (from 4 to 32 pounds depending on the commodity) before being fixed at 14 pounds by the Weights and Measures Act of 1835.
Common mistakes
Assuming a stone is used outside the British Isles—it is virtually unknown in the US, continental Europe, or most other countries. Also, forgetting that 1 stone = 14 pounds, not 10 or 12.
When is this conversion used?
Converting between stone and kilogram is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region. Body weight, grocery items, and luggage limits are commonly expressed in kilograms in most countries and pounds in the US and UK, making this one of the most frequently needed mass conversions.
How to convert stone to kilogram
To convert stone to kilogram, multiply the value by 6.35029318.
Conversion formula (from base unit)
x * 6.35029318
Measurement standards
The kilogram is defined by fixing the Planck constant to exactly 6.62607015 × 10⁻³⁴ joule-seconds, as established at the 26th General Conference on Weights and Measures in 2018. This ended the last SI definition based on a physical artefact.
Did you know?
The International Prototype of the Kilogram, a platinum-iridium cylinder stored near Paris since 1889, was found to have drifted by about 50 micrograms relative to its copies over a century — roughly the mass of a fingerprint.
| stone | kilograms |
|---|---|
| 0.1 | 0.63502932 |
| 0.5 | 3.17514659 |
| 1 | 6.35029318 |
| 2 | 12.70058636 |
| 5 | 31.7514659 |
| 10 | 63.5029318 |
| 25 | 158.7573295 |
| 50 | 317.514659 |
| 100 | 635.029318 |
| 250 | 1,587.573295 |
| 500 | 3,175.14659 |
| 1,000 | 6,350.29318 |
Common values
| stone | kilograms | |
|---|---|---|
| A paperclip | 0.00015747 stone | 0.001 kilograms |
| A smartphone | 0.02755778 stone | 0.175 kilograms |
| A bag of sugar | 0.15747304 stone | 1 kilogram |
| Average adult human | 11.02311311 stone | 70 kilograms |
| A small car | 188.9676533 stone | 1,200 kilograms |
Full stone conversion table
| Unit | Value | Factor |
|---|---|---|
| kilogram | 1 st = 6.35029318 kg | × 6.35029318 |
| gram | 1 st = 6,350.29318 g | × 6,350.29318 |
| pound | 1 st = 14 lb | × 14 |
| ounce | 1 st = 224 oz | × 224 |
| tonne | 1 st = 0.00635029 t | × 0.00635029 |
| milligram | 1 st = 6,350,293.18 mg | × 6,350,293.18 |
| microgram | 1 st = 6.350293e+09 µg | × 6.350293e+09 |
| short ton (US) | 1 st = 0.007 short ton | × 0.007 |
| long ton (UK) | 1 st = 0.00625 long ton | × 0.00625 |