What Is a Weight Converter?
A weight converter translates a measurement of mass or weight from one unit to another. In everyday language, people use weight and mass interchangeably, though physicists distinguish them: mass is the amount of matter in an object, while weight is the force gravity exerts on that mass. The conversion factors used here are based on mass, which is what scales and balances actually measure. The kilogram is the base unit of mass in the International System of Units (SI), defined since 2019 by the Planck constant rather than a physical artifact.
The imperial system uses the pound, defined internationally as exactly 0.45359237 kilograms. From that definition, one ounce is one-sixteenth of a pound, or 28.349523125 grams, and one stone is 14 pounds, or 6.35029318 kilograms. For a broader set of mass units including slugs and metric tons, see our Mass Calculator.
What This Calculator Does
This weight converter supports six common units: kilograms, grams, milligrams, pounds, ounces, and stones. Enter a value, choose the source and target units, and the result appears instantly. A swap button reverses the conversion, and a full table shows your input in every supported unit.
- Inputs: A numeric value, source unit, and target unit
- Outputs: Converted result, conversion details, and a table of all units
How the Conversion Works
The calculator first converts the input to kilograms, the base unit, then divides by the target unit's factor in kilograms. For example, converting 10 pounds to grams: 10 pounds times 0.45359237 equals 4.5359237 kilograms. Multiplying by 1,000 gives 4,535.9237 grams. For calculating weight as a force using gravitational acceleration, use our Weight Calculator.
Common Conversion Factors
- 1 pound = 0.45359237 kg (exact, by international definition)
- 1 ounce = 1/16 lb = 28.349523125 g (exact)
- 1 stone = 14 lb = 6.35029318 kg (exact)
- 1 kilogram = 1,000 g = 1,000,000 mg
- 1 kilogram = approximately 2.20462 lb
How to Use the Calculator
- Enter the weight value you want to convert
- Select the unit you are converting from
- Select the unit you are converting to
- Read the result, or click swap to reverse the direction
Real World Scenarios
A baker in London finds a recipe from New York that calls for 8 ounces of flour. Converting to grams: 8 times 28.349523125 equals 226.8 grams. A person tracking their weight sees 11 stone 6 pounds on a UK scale and wants kilograms: 11 times 6.35029318 plus 6 times 0.45359237 equals 72.57 kg. For converting other unit types, try our Unit Converter.