1 Stone equals 6.35029 Kilograms.
| Stone (st) | Kilogram (kg) |
|---|---|
| 0.001 st | 0.00635029 kg |
| 0.01 st | 0.0635029 kg |
| 0.1 st | 0.635029 kg |
| 1 st | 6.35029 kg |
| 2 st | 12.7006 kg |
| 5 st | 31.7515 kg |
| 10 st | 63.5029 kg |
| 25 st | 158.757 kg |
| 50 st | 317.515 kg |
| 100 st | 635.029 kg |
| 500 st | 3,175.15 kg |
| 1,000 st | 6,350.29 kg |
To convert Stone to Kilograms, multiply the value by 6.35029. This factor comes from the ratio of the two units' definitions: one Stone equals 6.35029 Kilograms.
For example: 1 Stone = 6.35029 Kilograms, and 10 Stone = 63.5029 Kilograms.
To convert in the reverse direction — from Kilograms to Stone — multiply by 0.157473.
The stone is a unit of weight equal to exactly 14 pounds (approximately 6.35 kg). It has been in use in England since at least the 14th century, originally varying by commodity — a stone of wool was 14 pounds, but a stone of beef was 8 pounds. The standardization at 14 pounds occurred gradually and was formalized in England in the 19th century, though many earlier regional variations persisted for centuries.
Today the stone is used almost exclusively in the United Kingdom and Ireland for expressing human body weight. A person who weighs 70 kilograms might describe themselves as "11 stone" in British conversation (70 ÷ 6.35 ≈ 11.02 stone). Doctor's surgeries, bathroom scales, and weight-loss discussions in the UK routinely use stone-and-pounds rather than kilograms alone. The BBC and UK newspapers typically include both when reporting body weight.
The stone is one of the few pre-metric units that has genuinely resisted metrication even in a country that otherwise uses metric for most official purposes. Attempts to replace it with kilograms have largely failed in the face of cultural attachment. Interestingly, no equivalent unit exists in the US system — Americans use pounds alone for body weight, making the stone a distinctly British-Irish phenomenon with almost no usage elsewhere in the world.
The kilogram is the SI base unit of mass — the unit from which all other mass units in the metric system derive. For most of its history (1889–2019), it was defined by a physical artifact: the International Prototype Kilogram (IPK), a cylinder of platinum-iridium alloy stored in a vault near Paris. In 2019, the definition was revolutionized: the kilogram is now defined by fixing the numerical value of the Planck constant to exactly 6.62607015 × 10⁻³⁴ J·s, making it the first base unit defined purely through a fundamental constant of nature.
In everyday life, the kilogram is the standard unit for body weight, food, and loads across most of the world. A liter of water has a mass of almost exactly one kilogram (0.9998 kg at room temperature). A typical adult human weighs 60–90 kg. A car weighs roughly 1,500 kg. The kilogram thus spans the range from a bag of flour to a small vehicle without requiring a change of units.
The change from artifact to fundamental-constant definition was scientifically momentous. For 130 years, the IPK was losing mass at a rate of about 50 micrograms per century relative to its official copies — a drift that was unmeasurable until metrology improved enough to notice it. The new definition eliminates this drift entirely: the kilogram is now as stable as the Planck constant itself, which is believed to be truly invariant across space and time.
1 Stone equals 6.35029 Kilograms.
To convert Stone to Kilograms, multiply by 6.35029. For example, 1 Stone = 6.35029 Kilograms.
1 Kilogram equals 0.157473 Stone.