Weight Calculator
A 70 kg person weighs 686.465 N under standard gravity, from W = mg with g = 9.80665 m/s². On the Moon the same person weighs about one sixth as much.
686.4655 N
Full answer, then cut to fewer decimals (not rounded):
- 686.4655 N
- 686.465 N
- 686.46 N
- 686.4 N
- In kgf (kilogram-force)
- 70 kgf
- In lbf (pound-force)
- 154.3235835 lbf
- Ratio to Earth weight
- 1
| Body | g (m/s²) | Weight (N) | Weight (kgf) |
|---|---|---|---|
| Earth | 9.80665 | 686.465 | 70 |
| Moon | 1.62 | 113.4 | 11.5636 |
| Mercury | 3.7 | 259 | 26.4106 |
| Venus | 8.87 | 620.9 | 63.3142 |
| Mars | 3.71 | 259.7 | 26.482 |
| Jupiter | 24.79 | 1735.3 | 176.951 |
| Saturn | 10.44 | 730.8 | 74.5209 |
| Uranus | 8.69 | 608.3 | 62.0293 |
| Neptune | 11.15 | 780.5 | 79.5889 |
| Pluto | 0.62 | 43.4 | 4.42557 |
| Sun | 274 | 19180 | 1955.82 |
Step-by-step solution
- W = m × g
- W = 70 kg × 9.80665 m/s²
- W = 686.4655 N
Weight Formula
W = m g
W weight (N), m mass (kg), g gravitational acceleration (9.80665 m/s² standard on Earth)
Worked Example
A 70 kg person standing on Earth:
- W = m × g
- W = 70 kg × 9.80665 m/s²
- W = 686.4655 N
In lbf (pound-force): 154.3235835 lbf · Ratio to Earth weight: 1
| Body | g (m/s²) | Weight (N) | Weight (kgf) |
|---|---|---|---|
| Earth | 9.80665 | 686.465 | 70 |
| Moon | 1.62 | 113.4 | 11.5636 |
| Mercury | 3.7 | 259 | 26.4106 |
| Venus | 8.87 | 620.9 | 63.3142 |
| Mars | 3.71 | 259.7 | 26.482 |
| Jupiter | 24.79 | 1735.3 | 176.951 |
| Saturn | 10.44 | 730.8 | 74.5209 |
| Uranus | 8.69 | 608.3 | 62.0293 |
| Neptune | 11.15 | 780.5 | 79.5889 |
| Pluto | 0.62 | 43.4 | 4.42557 |
| Sun | 274 | 19180 | 1955.82 |
Kilogram-force
One kilogram-force (kgf) is the weight of 1 kg under standard gravity, exactly 9.80665 N. Weight in kgf on Earth therefore equals the mass in kilograms, which is why everyday language treats them as the same.
More Forces and Newton’s Laws Calculators
-
Gravitational Force Calculator
F = G m₁ m₂ / r²
G = 6.67430 × 10⁻¹¹ N·m²/kg², m₁ and m₂ the masses, r the distance between their centres
Example: Earth (5.972 × 10²⁴ kg) and the Moon (7.348 × 10²² kg) 384,400 km apart: Gravitational force F = 1.98211 × 10²⁰ N.
-
Newton's Second Law Calculator
F = m a
F net force (N), m mass (kg), a acceleration (m/s²)
Example: A 12 kg trolley accelerating at 2.5 m/s²: Net force F = 30 N.
-
Centripetal Force Calculator
F = m v² / r
m mass, v speed, r radius of the circle; a = v²/r, ω = v/r
Example: A 1000 kg car taking a 50 m radius curve at 10 m/s: Centripetal force F = 2000 N.
-
Hooke's Law Calculator
F = k x
F spring force, k spring constant (stiffness), x extension or compression; energy E = ½kx²
Example: A spring with k = 200 N/m stretched 0.25 m: Spring force F = 50 N.
Frequently asked questions
What is the difference between mass and weight?
Mass (kg) is the amount of matter and is the same everywhere; weight (N) is the gravitational force on it and depends on g. Bathroom scales show mass by assuming Earth’s gravity.
Why do textbooks use 9.8 or 9.81?
They round standard gravity, 9.80665 m/s². Real g varies from about 9.78 m/s² at the equator to 9.83 m/s² at the poles.
Where do the planet values come from?
Surface gravity from NASA’s Planetary Fact Sheet; for gas giants it is the value at the 1 bar pressure level.
Sources
- Planetary Fact Sheet, NASA Goddard Space Flight Center .
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). Weight Calculator. Retrieved October 25, 2026, from https://scientificconverters.com/calculators/weight-calculator/
IEEE
Scientific Converters, "Weight Calculator," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/calculators/weight-calculator/