Weight Calculator
Convert mass to weight under Earth or any other gravity, and between units.
About Weight Calculator
Weight is the gravitational force on a mass: W = m × g. On Earth, g ≈ 9.807 m/s² (varies slightly with latitude and altitude). On the Moon g ≈ 1.62 m/s², so a 70 kg person weighs about 686 N on Earth but only 113 N on the Moon — though their mass remains 70 kg everywhere.
Formula
Weight
Weight (N) = Mass (kg) × Gravitational acceleration (m/s²)
- W
- Weight in Newtons
- m
- Mass in kilograms
- g
- Gravitational acceleration in m/s²
Worked example
With the default values below, Weight Calculator returns Weight (Newtons) of 686.4655. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Massaccepts 0–1,000,000,000,000
- 70
- Mass Unitone of kg, g, lb, oz, t, slug
- kg
- Gravitational Bodyone of Earth, Moon, Mars, Venus, Mercury, Jupiter, Saturn, Uranus, Neptune, Pluto, Sun
- Earth
- Show all planets?
- No
Results
- Weight (Newtons)
- 686.4655 N
- Weight (kgf)
- 70.0000 kgf
- Weight (lbf)
- 154.3236 lbf
- Mass
- 70.0000 kg
- Gravity Body
- Earth
- g
- 9.80665 m/s²
Step by step
- 1Mass in kg= 70 kg
- 2Gravitational acceleration on Earth= 9.80665 m/s²
- 3Weight = mass × g= 686.4655 N
- 4In kilogram-force (kgf)= 70 kgf
- 5In pound-force (lbf)= 154.3236 lbf
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 5 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
What is my weight on Mars?
Mars has about 38% of Earth's surface gravity (3.72 m/s² vs 9.81 m/s²). A 70 kg person would weigh about 260 N on Mars compared to 686 N on Earth — less than 40% of their Earth weight.
What is the difference between mass and weight?
Mass (kilograms) measures the amount of matter — it's the same everywhere. Weight (Newtons) is the gravitational force on that mass, which varies with the local gravitational acceleration g.
Why does a bathroom scale show kilograms, not Newtons?
Bathroom scales display mass (kilograms) or kilogram-force (kgf), not scientific Newtons. Because g is approximately constant on Earth's surface, scales are calibrated to divide the force reading by 9.807 and show kg. In physics, weight is always a force in Newtons.
Why is the Sun's gravity so high?
The Sun's surface gravity is 274 m/s² — about 28 times Earth's — because of its enormous mass (333,000 × Earth). However, the Sun has no solid surface; spacecraft encounter the Sun's gravity from orbit, not its surface.