Acceleration Due to Gravity Calculator

About the Acceleration Due to Gravity Calculator

The acceleration due to gravity (g) is not a fixed constant — it varies with altitude, latitude, and the celestial body you are on. At Earth's sea level, g averages 9.80665 m/s², but this value decreases as you climb higher and varies slightly between the equator and the poles due to Earth's oblate shape and rotation.

This gravity calculator lets you explore how g changes across a wide range of conditions. Select from eight celestial bodies — Earth, Moon, Mars, Jupiter, Venus, Mercury, Saturn, and the Sun — and adjust the altitude to see how gravity weakens with distance. For Earth, the latitude correction accounts for centrifugal effects and the planet's oblate spheroid shape using the International Gravity Formula.

Whether you are studying orbital mechanics, comparing planetary environments, or simply curious why astronauts feel weightless on the ISS (spoiler: g is still about 89% of sea level there), it gives the answers with full context and reference data.

When This Page Helps

Understanding gravitational acceleration variations is essential for aerospace engineering, satellite design, geophysics, and planetary science. It gives instant results for any combination of altitude, latitude, and celestial body, saving time on manual calculations with the universal gravitation formula.

The built-in comparison tables and presets make it easy to explore how gravity changes from sea level to orbit, or compare conditions across the solar system — all in one tool.

How to Use the Inputs

1. Select a celestial body from the dropdown (Earth, Moon, Mars, etc.).
2. Enter the altitude above the surface in your preferred unit.
3. For Earth, adjust the latitude to see polar vs equatorial variation.
4. Enter an object mass to see the corresponding weight.
5. Use preset buttons for common scenarios like Mt Everest or ISS orbit.
6. Compare gravity values across bodies in the reference table.

Example Calculation

Tips & Best Practices

• Latitude correction only applies to Earth and is most significant at low altitudes.
• The escape velocity output tells you the minimum speed needed to leave the body's gravitational influence.
• For very high altitudes, remember that 'weightlessness' is about free fall, not zero gravity.
• Compare planet gravities to understand why Mars rovers weigh less than on Earth.
• The percentage display helps quickly gauge how location affects gravity.
• Use altitude in km for space-related calculations and meters for terrestrial ones.

How Gravity Varies with Altitude

Gravity follows an inverse-square law: doubling the distance from a body's center reduces g to one-quarter. Near Earth's surface, the change is approximately −0.3% per kilometer of altitude. At 400 km (ISS orbit), g drops to about 89% of the sea-level value. At geostationary orbit (35,786 km), it falls to just 2.2%.

The Role of Latitude

Earth's rotation creates a centrifugal effect that slightly reduces effective gravity at the equator. Combined with the equatorial bulge (Earth's radius is about 21 km larger at the equator than at the poles), gravity at the equator is roughly 0.53% weaker than at the poles. The International Gravity Formula quantifies this variation precisely.

Gravity Across the Solar System

Surface gravity varies enormously across celestial bodies. The Moon's 1.62 m/s² makes lunar walking bouncy and slow. Mars at 3.72 m/s² is a key factor in planning crewed missions. Jupiter's crushing 24.8 m/s² would make standing impossible for humans. These differences fundamentally shape how we design spacecraft and plan extraterrestrial activities.

Frequently Asked Questions

• Why is gravity different at the poles vs the equator?

  Earth is not a perfect sphere — it bulges at the equator. The poles are closer to Earth's center, so gravity is slightly stronger there. Additionally, the centrifugal effect from Earth's rotation reduces effective gravity at the equator.

• Do astronauts on the ISS experience zero gravity?

  Not exactly. At ISS altitude (408 km), g is still about 8.7 m/s² (89% of sea level). Astronauts feel weightless because they are in continuous free fall — orbiting at just the right speed to keep falling around Earth.

• How much would I weigh on the Moon?

  The Moon's surface gravity is about 1.62 m/s², roughly 16.5% of Earth's. A 70 kg person would weigh about 113 N on the Moon compared to 687 N on Earth.

• Does altitude significantly affect gravity?

  For everyday altitudes, the change is small. At the top of Mt Everest, g decreases by only 0.3%. But at satellite altitudes (hundreds of km), the reduction becomes significant.

• What is the standard value of g?

  The standard acceleration due to gravity is exactly 9.80665 m/s², defined by the 3rd General Conference on Weights and Measures in 1901. This is the value used in most physics calculations.

• Why is gravity on Jupiter so strong?

  Jupiter's surface gravity is about 24.8 m/s² (2.53 g), mainly because of its enormous mass (318 times Earth's). Despite Jupiter's large radius, the mass dominates.