Surface Gravity Calculator
Calculate Newtonian gravitational acceleration from a spherical body mass and radius.
Calculate locally
No account, API or uploaded inputs. All calculations run in this browser.
Worked example
An ideal body of mass 1/G ≈ 1.498284464 × 10¹⁰ kg and radius 1 metre produces approximately 1 m/s². Earth-like mass 5.972 × 10²⁴ kg and radius 6371 km give approximately 9.82 m/s².
Method and units
g = GM/r², with G = 6.67430 × 10⁻¹¹ m³ kg⁻¹ s⁻² and radius converted from kilometres to metres. Divide by standard gravity g₀ = 9.80665 m/s² for the dimensionless comparison.
What this result means
Assumes a spherical, nonrotating body and a Newtonian exterior field. Rotation, latitude, shape and relativistic effects are omitted. Standard gravity is a conventional reference, not every local Earth reading. This is acceleration rather than mass or force; multiply by a test mass for force in newtons.