Weight & Mass Converter
Convert between 10 units of weight and mass. Kilograms, pounds, grams, ounces, stone, metric tons, short and long tons, carats, and milligrams.
About the Weight & Mass Converter
Mass and weight are related but distinct concepts. Mass is the amount of matter in an object (measured in kg), while weight is the gravitational force acting on that mass (measured in newtons). In everyday usage they are used interchangeably. The kilogram was redefined in 2019 in terms of Planck's constant, making it the most precisely defined unit in history.
- ›The kilogram was redefined on 20 May 2019 using Planck's constant (6.626 × 10⁻³⁴ J·s)
- ›One pound is defined as exactly 0.45359237 kilograms
- ›The carat used for gemstones equals exactly 0.2 grams (200 milligrams)
- ›A metric ton (1,000 kg) differs from a US short ton (907.18 kg) and a UK long ton (1,016 kg)
Frequently Asked Questions
What units does the Weight & Mass Converter support?
The Weight & Mass Converter supports multiple units with instant conversion. Convert between 10 units of weight and mass. Kilograms, pounds, grams, ounces, stone, metric tons, short and long tons, carats, and milligrams. All results use SI-validated constants accurate to 8 significant figures.
Is this Weight & Mass Converter free?
Yes — completely free. No registration, no limits. Works on all devices including mobile.
How accurate is this converter?
Accurate to 8 significant figures using precise mathematical constants validated against international SI standards (NIST and ISO 80000).