Kilogram (kg)
The kilogram (kg) is the SI base unit of mass. Since 2019 it is defined by fixing the Planck constant, replacing the platinum-iridium prototype kept near Paris.
Symbol: kg
Quantity: mass (commonly called weight)
SI relation: kg is the coherent SI unit of weight and mass.
Derivation: SI base unit, fixed by the Planck constant h = 6.626 070 15 × 10⁻³⁴ J·s
Exact: yes, by definition
History
From 1889 to 2019 the kilogram was the mass of the International Prototype Kilogram, the last SI unit defined by a physical object.
Typical uses
- Body weight and food packaging
- Freight, baggage allowances (e.g. 23 kg)
- Engineering mass and load calculations
Convert kilograms to other units
| Conversion | 1 kg equals | Reverse |
|---|---|---|
| kilogram to gram | 1000 g | gram to kilogram |
| kilogram to milligram | 1000000 mg | milligram to kilogram |
| kilogram to pound | 2.204622622 lb | pound to kilogram |
| kilogram to ounce | 35.27396195 oz | ounce to kilogram |
| kilogram to microgram | 1000000000 µg | microgram to kilogram |
| kilogram to metric ton | 0.001 t | metric ton to kilogram |
| kilogram to stone | 0.1574730444 st | stone to kilogram |
| kilogram to short ton | 0.001102311311 ton (US) | short ton to kilogram |
| kilogram to troy ounce | 32.15074657 oz t | troy ounce to kilogram |
| kilogram to long ton | 0.0009842065276 ton (UK) | long ton to kilogram |
| kilogram to grain | 15432.35835 gr | grain to kilogram |
| kilogram to carat | 5000 ct | carat to kilogram |
Open the Weight and Mass Converter to convert any value between all units.
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Section 2.3.1, base unit definitions.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Kilogram (kg). Retrieved October 17, 2026, from https://scientificconverters.com/units/kilogram/
IEEE
Scientific Converters, "Kilogram (kg)," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/units/kilogram/