Weight Calculator
Convert weight between kilograms, pounds, stone, ounces, and grams.
Convert between all major weight and mass units instantly.
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How to Convert Between Weight Units
Metric System
The metric system uses the kilogram (kg) as its base unit of mass. All other metric units are powers of ten — grams (1/1,000 kg), milligrams (1/1,000,000 kg), and metric tons (1,000 kg). It is the global scientific and commercial standard.
Imperial & US Customary
The pound (lb) is the primary everyday unit in the US and UK. There are 16 ounces to a pound. A US short ton is 2,000 lb; a UK long ton is 2,240 lb. The systems share names but differ in some unit sizes. For converting between all weight and mass units, use the unit converter.
Stone
One stone equals exactly 14 pounds (approximately 6.35 kg). Stones are commonly used in the UK and Ireland to express body weight. Someone who is "11 stone 4" weighs 158 lb or about 71.7 kg. To check whether this weight is healthy for your height, try the BMI calculator.
Weight vs Mass
Scientifically, weight is a force (Newtons) while mass is the amount of matter (kilograms). In everyday use the terms are interchangeable since we measure under standard Earth gravity. An atomic mass unit (u) is defined as 1/12 the mass of a carbon-12 atom.
Worked example
12 stone 4 lbs in other units: 12 st × 14 + 4 lb = 172 lbs. 172 × 0.45359 = 78.0 kg; 78,016 g; 0.0780 metric tons; 2,752 oz. To check if this is a healthy weight for your height, try the BMI calculator.
Frequently Asked Questions
How many kilograms are in a pound?
One pound equals exactly 0.45359237 kilograms. One kilogram equals approximately 2.20462 pounds. Enter any value in the weight converter above to convert instantly between kilograms, pounds, stone, ounces, and more.
How many pounds are in a stone?
One stone equals exactly 14 pounds, or approximately 6.35 kilograms. Stone is commonly used in the UK and Ireland to express body weight — someone described as '11 stone 4' weighs 158 pounds (about 71.7 kg).
What is the difference between a metric ton and a US ton?
A metric ton (tonne) equals 1,000 kg (approximately 2,204.6 lb). A US short ton equals 2,000 lb (approximately 907.2 kg). A UK long ton equals 2,240 lb (approximately 1,016 kg). The metric ton is the international standard for most commercial purposes.
Is weight the same as mass?
Scientifically, mass is the amount of matter in an object (kilograms) while weight is the gravitational force acting on it (Newtons). In everyday use the terms are interchangeable at standard Earth gravity. On the Moon, your mass is unchanged but your weight would be about one-sixth what it is on Earth.
Evidence & Methodology
How This Page Is Grounded
Method
Converts mass using defined relationships between kilograms, pounds, ounces and stones.
Important limitation: Displayed values are rounded to the precision shown; this converts mass units and is not a health assessment.
Primary Sources
- The International System of Units (SI Brochure) International Bureau of Weights and Measures
- SI units National Institute of Standards and Technology
Quality Checks
Exact factors and round-trip conversions are checked at common and boundary values.
See how sources are selected and corrections are handled in our Editorial & Calculation Methodology, and which automated checks this page has to pass in How We Test.