Weight / Mass Converter
Convert between kg, lbs, stone, ounces, grams, and more.
BSc Physics (Hons), MEng Mechanical Engineering
Physicist and engineer focused on translating complex scientific and mathematical calculations into accessible everyday tools.
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About the Weight / Mass Converter
Weight and mass conversions are among the most commonly searched unit conversions globally. "Lbs to kg," "stone to kg," and "kg to lbs" are searched millions of times each month by people managing their health, following recipes, understanding parcel shipping limits, reading foreign product specifications, and tracking fitness progress. The core challenge is that different regions of the world use different systems — the UK uses stone and pounds for human weight, kilograms in scientific and food contexts; the US uses pounds almost exclusively; the rest of the world uses kilograms.
Technically, weight and mass are different concepts. Mass is the amount of matter in an object (measured in kg, g, lb etc.) and is constant regardless of location. Weight is the gravitational force on that mass (measured in Newtons) and varies slightly by location — you would weigh about 0.5% less on a mountaintop than at sea level. In everyday life, "weight" and "mass" are used interchangeably, and all common scales and this calculator measure mass.
The stone is a unit unique to the British Isles for measuring human body weight. 1 stone = 14 pounds = 6.35029 kg. A person weighing "12 stone 4 pounds" weighs (12 × 14) + 4 = 172 pounds = 78.0 kg. The stone is not used in any official scientific context but remains culturally entrenched in the UK for body weight.
How it works
Key conversion factors (exact where stated): 1 kg = 2.20462 lb 1 lb = 0.453592 kg (exact: 0.45359237 kg) 1 stone = 14 lb = 6.35029 kg 1 oz = 28.3495 g 1 tonne = 1,000 kg = 2,204.62 lb Stone + lbs from kg: Total lbs = kg ÷ 0.453592 Stone = floor(total lbs ÷ 14) Remaining lbs = total lbs − (stone × 14)
Where
kgKilogram — the SI base unit of masslbPound — the primary US unit; also used in UK for some contextsstStone — 14 pounds; used in UK/Ireland for human body weightWorked example
Convert 75 kg to stone and pounds:
75 kg ÷ 0.453592 = 165.35 lb
Stone = floor(165.35 ÷ 14) = floor(11.81) = 11 stone
Remaining = 165.35 − (11 × 14) = 165.35 − 154 = 11.35 lb
Result: 11 stone 11.4 lb
Convert 185 lb to kg:
185 × 0.453592 = 83.91 kg
Tips to improve your result
- 1.
To quickly convert kg to lbs, multiply by 2.2 (for rough estimates) or 2.205 (for better accuracy). To convert lbs to kg, divide by 2.2.
- 2.
For stone: multiply stones by 14 to get total pounds first, then convert. E.g. 13 stone 5 lb = (13×14) + 5 = 187 lb = 84.8 kg.
- 3.
Medication doses and clinical guidelines always use kilograms. If your weight is in stone, multiply stone by 6.35 to get kilograms for medical purposes.
- 4.
Parcel and luggage weight limits are typically in kilograms. Common airline hand luggage limits: 7 kg (carry-on) and 20–23 kg (checked bag).
- 5.
The avoirdupois pound (used for everyday weight) is different from the troy pound (used for precious metals). 1 troy pound = 12 troy ounces = 373.24 g (lighter than the avoirdupois pound of 453.59 g).