Weight Converter
Convert between metric and imperial weight units instantly.
Reviewed by Richard Ross · Last updated April 2026
How Weight Converter works
Metric and imperial weight
The SI unit of weight (mass) is the kilogram. 1 kg = 1,000 grams. 1 tonne = 1,000 kg. Imperial units: 16 oz = 1 lb; 14 lb = 1 stone.
Key conversions
1 kg = 2.20462 lb. 1 stone = 6.35029 kg = 14 lb. 1 lb = 453.592 g. 1 oz = 28.3495 g.
Stone: a distinctly British unit
Stone is used almost exclusively in the UK and Ireland for measuring body weight. Most other countries use kilograms. When attending a UK GP or NHS clinic, your weight is typically recorded in kilograms, but many British adults still think of their weight in stone and pounds. Knowing your weight in both systems is useful for interpreting NHS BMI charts and international health research.
Real-world use cases
Weight conversions arise in cooking (recipes switching between grams and ounces), parcel shipping (couriers charge by kg), luggage allowances (airlines specify limits in kg), and sport (boxing weight classes use both kg and stone/lb in the UK). Food packaging sold in the UK must display weight in metric (grams or kilograms) by law, though imperial equivalents can also be shown voluntarily.
Precision and common mistakes
A common error is confusing mass and weight in physics — strictly, weight is a force measured in newtons, while mass is measured in kilograms. For everyday purposes the terms are interchangeable. Another pitfall: stone always contains exactly 14 pounds, so 11 stone 7 pounds is not the same as 11.7 stone (which would be 11 stone 9.8 lb). Always split the fractional stone into pounds correctly.
Frequently asked questions
How many pounds in a kilogram?
1 kg = 2.20462 lb. So 70 kg ≈ 154.3 lb.
How many pounds in a stone?
Exactly 14 pounds in 1 stone. So 11 stone = 154 lb.
How many kg in a stone?
1 stone = 6.35029 kg. So 11 stone ≈ 69.85 kg.
What is 70 kg in stone and pounds?
70 kg ÷ 6.35029 = 11.023 stone = 11 stone 0.3 lb ≈ 11 stone.
How do I convert ounces to grams?
Multiply ounces by 28.3495. So 8 oz = 226.8 g. This is useful for baking when following US recipes that list ingredient weights in ounces rather than grams.
What is the difference between a tonne, a ton, and a long ton?
A metric tonne = 1,000 kg. A US short ton = 2,000 lb ≈ 907 kg. A UK long ton = 2,240 lb ≈ 1,016 kg. The metric tonne is standard in the UK for commercial and scientific use.
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