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Stones to KG Converter

What Is a Stone?

A stone (abbreviated "st") is an Imperial unit of weight equal to 14 pounds or approximately 6.35 kilograms. It is commonly used in the United Kingdom and Ireland to express body weight. For example, a person weighing 11 stone 4 pounds would weigh about 71.7 kg. The stone has been used since medieval times for trade, originally varying by commodity — a stone of wool weighed differently than a stone of glass. In 1835, the British Weights and Measures Act standardized the stone at 14 pounds. While most of the world uses kilograms for body weight, the stone remains the preferred unit in casual conversation throughout the UK and Ireland. You'll hear it used in everyday life, fitness discussions, and even on British TV shows, making this conversion essential for international communication.

How to Convert Stones to Kilograms

The conversion formula is straightforward: multiply the number of stones by 6.35029318 to get kilograms. For example, 10 stones × 6.35029 = 63.5 kg. If you have stones and pounds (like 11 st 7 lbs), first convert everything to pounds (11 × 14 + 7 = 161 lbs), then multiply by 0.453592 to get kilograms (161 × 0.453592 = 73.03 kg). Alternatively, convert the stones portion and pounds portion separately: 11 st = 69.85 kg, 7 lbs = 3.18 kg, total = 73.03 kg. For a quick mental approximation, multiply stones by 6.35 — this is accurate to within 0.01% of the exact conversion factor.

Frequently Asked Questions

How many kilograms are in 1 stone?

1 stone equals exactly 6.35029318 kilograms. For quick mental math, 1 stone ≈ 6.35 kg. This conversion factor is defined by international agreement and does not change.

How do I convert stones and pounds to kg?

Convert the stones portion and pounds portion separately, then add them. Multiply stones by 6.35029 and pounds by 0.45359, then sum both results. For example, 12 st 8 lbs = (12 × 6.35029) + (8 × 0.45359) = 76.20 + 3.63 = 79.83 kg.

Why does the UK still use stones for weight?

Cultural habit and tradition. Despite the UK officially adopting the metric system, stones remain deeply embedded in everyday conversation about body weight. Most British people learned their weight in stones from family and friends, and the habit persists across generations. Medical settings increasingly use kilograms, but casual usage of stones shows no signs of disappearing.

Is a stone the same in all countries?

The modern stone is standardized at 14 pounds (6.35029 kg) since the 1835 British Weights and Measures Act. Historically, the stone varied by region and commodity. Today, it is only commonly used in the UK and Ireland. The United States, Canada, Australia, and most other countries do not use the stone.

How do I convert kg back to stones?

Divide the kilogram value by 6.35029 to get stones. For example, 80 kg ÷ 6.35029 = 12.598 stones, which is 12 stone 8.4 pounds. To get the remaining pounds: take the decimal portion (0.598) and multiply by 14 = 8.4 pounds.

What is 10 stone in kg?

10 stone equals 63.503 kg (or approximately 63.5 kg). This is also equal to 140 pounds. 10 stone is a commonly referenced benchmark weight in UK fitness and health discussions.