By Zencalcy Editorial TeamLast reviewed About us
Mass is the amount of matter in an object and does not change with location, while weight is the gravitational force on that mass and does. This calculator applies W = mg with the gravity you choose, so the same 70 kg person can weigh different amounts on Earth, the Moon or Mars.
Convert between mass and weight at any gravitational acceleration.
W = m g
W is weight in newtons, m is mass in kilograms and g is the local gravitational acceleration. Standard gravity is 9.80665 m/s²; the Moon is about 1.62 m/s² and Mars about 3.71 m/s².
| Symbol | Meaning |
|---|---|
| W | Weight, in newtons. |
| m | Mass, in kilograms. |
| g | Gravitational acceleration at the location, in m/s². |
At 1 g a 70 kg person weighs 70 × 9.80665 = 686.5 N, which is 154.3 lbf or 70 kgf. On the Moon the same mass would weigh only about 113 N.
Continue with the Apparent Weight in an Elevator, Banked Turn Calculator, or the Centripetal Force Calculator — or browse more dynamics tools and all physics calculators.
Slightly. Earth's rotation and its equatorial bulge make effective gravity about 0.5% lower at the equator than at the poles, so a 70 kg person's weight differs by roughly 3 N.
Results are computed from the standard equations of classical mechanics. Unit conversions use the SI definitions published by NIST. Air resistance is ignored unless the calculator names a drag model.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026