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    Gravity

    Surface Gravity Calculator

    Gravitational acceleration at the surface of any planet, moon or star from its mass and radius.

    g = G · M / R²

    Inputs

    Results

    Surface gravity
    9.8203 m/s²
    Escape velocity
    11.1862 km/s
    Mean density
    5.513 g/cm³
    Worked solution
    1. g = 6.6743 × 10^-11 × 5.9722 × 10^24 / (6,371,000)² = 9.8203 m/s²
    2. g / g₀ = 1.001

    How the result changes

    Gravity (m/s²) plotted against Radius (km), from one quarter to four times your input, with your input marked.0501001505,00010,00015,00020,00025,000Radius (km)Gravity (m/s²)your input
    Gravity vs radius

    How it works

    Surface gravity grows with mass but falls with the square of radius. Saturn is 95 times Earth's mass, yet its gravity at the 1-bar level is only about 9 m/s² because it is so large.

    Variables

    • g — surface gravitational acceleration
    • M — mass of the body
    • R — radius of the body

    Assumptions and limits

    • Spherical, non-rotating body (rotation slightly reduces effective gravity at the equator)

    For education only. These models are simplified and are not suitable for spacecraft navigation or safety-critical engineering. See our scientific accuracy policy.