How to use this calculator
- Enter or choose mass.
- Enter or choose mass unit.
- Enter or choose where.
- The weight updates as you type. Use Copy result or Share to keep it.
Method
W = m × g; kgf = W ÷ 9.80665; lbf = W ÷ (0.45359237 × 9.80665)
- W
- weight, a force in newtons (N)
- m
- mass in kg (1 lb = 0.45359237 kg)
- g
- gravitational acceleration at the surface, in m/s²
Worked example
- On Earth: W = 70 × 9.80665 = 686.47 N.
- On the Moon (g = 1.6 m/s²): W = 70 × 1.6 = 112 N.
- 1.6 ÷ 9.80665 = 16.3% of Earth weight.
A 70 kg person weighs about 686 N on Earth but only 112 N on the Moon, about 16% as much.
What the result means
A bathroom scale shows weight divided by Earth’s gravity, so on the Moon the same scale would read about 11.4 kg for a 70 kg person, even though their mass has not changed.
Assumptions and limits
- Planetary values are surface gravity at the equator, rounded to 0.1 m/s², from NASA’s planetary fact sheet. Earth uses standard gravity, 9.80665 m/s².
- Real gravity on Earth varies by about 0.5% with latitude and altitude.
- For the gas giants, “surface” means the level where atmospheric pressure is 1 bar.
Questions
Is kilogram-force the same as kilogram?
No. Kilogram is mass; kilogram-force is the weight of 1 kg at standard gravity (9.80665 N). On Earth the numbers match, which is why everyday language mixes them up.
Why is my weight on Saturn similar to Earth?
Saturn is very massive but also very large, so at the level of its cloud tops gravity is about 9.0 m/s², close to Earth’s.