Calculate gravitational force

Estimate Newtonian attraction between two point masses at a centre-to-centre separation.

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ToolGravitational Force Calculator
Input
Output
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Preview

How it works

Newton’s law gives F = Gm₁m₂ ÷ r² using kilograms, metres, and the gravitational constant. The result is rounded to four significant digits for display.

  • The stored G value is used as a universal constant.
  • Point-mass geometry omits shape, rotation, altitude, and local-field corrections.

Worked example

Two 1000kg masses, 1m apart
A lab-scale example, the same setup a Cavendish-style experiment measures
Input
											Mass1 kg: 1000
Mass2 kg: 1000
Distance metres: 1
Output
												Force newtons: 0.00006674
Force pound force: 0.000015
Acceleration on mass1: 6.674e-8
Acceleration on mass2: 6.674e-8

When to use this

Mechanics lessons calculate mass attraction, orbital estimates use centre separation, and engineering checks compare force scales.

Edge cases

  • Doubling distance quarters force because distance is squared.
  • Surface-to-surface gap is not centre-to-centre separation for extended bodies.
  • Very small forces can round to zero in the display while remaining nonzero internally.

References