Mass Calculator
Calculate and convert mass between kilograms, pounds, grams, ounces, and other units.
Frequently Asked Questions
What is the difference between mass and weight?
Mass is the amount of matter in an object, measured in kilograms and constant regardless of location. Weight is the gravitational force acting on that mass, measured in newtons, and varies depending on gravitational pull. On Earth, a 70 kg person weighs about 686 newtons. On the Moon, their mass is still 70 kg but they weigh only about 114 newtons. In everyday conversation, "weight" is used loosely to mean mass, but in physics they are distinct concepts with different units.
What are some common mass units and their relationships?
Common mass units include: 1 kilogram (kg) = 1,000 grams (g) = 2.20462 pounds (lb). One pound = 16 ounces = 453.592 grams. One metric ton = 1,000 kg ≈ 2,204.62 pounds. The US ton (short ton) = 2,000 pounds ≈ 907 kg. The UK ton (long ton) = 2,240 pounds ≈ 1,016 kg. These distinctions matter in shipping, international trade, and scientific measurements where using the wrong unit type can cause costly or even dangerous errors.
How is mass measured scientifically?
Scientists measure mass using balances and scales calibrated to standardized weights. The kilogram was historically defined by a physical platinum-iridium cylinder stored in France, but in 2019 it was redefined in terms of fundamental physical constants — specifically Planck's constant — to improve precision and universality. Laboratory balances can measure mass to micrograms or even nanograms for very precise scientific work. In space, mass is measured using inertia-based methods since gravity is absent and conventional scales don't work.