How it works
Every mass attracts every other mass with a force proportional to the product of the masses and inversely proportional to the square of the distance between their centers.
The gravitational constant G = 6.67430 × 10⁻¹¹ m³ kg⁻¹ s⁻² (CODATA 2018) is tiny, so gravity between everyday objects is almost undetectable. It dominates only when at least one mass is enormous, like a planet or star.
The defaults show the Earth–Moon pull, about 1.98 × 10²⁰ N. Measure distance between centers of mass, not surfaces.
Formula
F = G × m₁ × m₂ ÷ r², G = 6.67430 × 10⁻¹¹ m³ kg⁻¹ s⁻²
Questions people ask
How strong is gravity between two people?
Two 70 kg people 1 m apart attract each other with about 3.3 × 10⁻⁷ N, roughly the weight of a few grains of dust.
Why does doubling distance quarter the force?
Gravity spreads over the surface of a sphere, whose area grows with r². Twice as far means the force is spread over four times the area.
Can I use this for weight on another planet?
Yes. Put the planet’s mass as mass 1, your mass as mass 2 and the planet’s radius as the distance. The acceleration of mass 2 is the surface gravity.