When to use this calculator
Estimate gravity at a spherical body’s surface from its gravitational parameter. Spherical-body approximation without rotation or local gravitational anomalies.
Explore the orbits & escape calculators for other questions in this topic. For a related calculation, use the Distance From Modulus Calculator: Recover astronomical distance from an entered distance modulus.
PUTTING IT INTO PRACTICE
Surface Gravity From Mu: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Gravitational parameter (km³/s²) | 400,000 |
| Surface radius (km) | 10,000 |
| Result | 4 m/s² |
- Check the input labels and enter the example values above.
- Apply the relationship: Surface acceleration = μ/radius², converted from km/s² to m/s².
- The result is 4 m/s², rounded for display.
How to interpret your result
Spherical-body approximation without rotation or local gravitational anomalies.
Use radius from the centre of the attracting body, not altitude above its surface. Choose the gravitational parameter of the correct primary. Drag, rotation and other bodies are excluded from these simple models.
Frequently asked questions
Can I use altitude directly as orbital radius?
No. Add the central body’s radius to altitude when a formula requires distance from its centre.
When is the surface gravity from mu calculator useful?
Estimate gravity at a spherical body’s surface from its gravitational parameter. Spherical-body approximation without rotation or local gravitational anomalies.
How do I use the surface gravity from mu calculator?
Enter gravitational parameter (km³/s²), surface radius (km). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Surface acceleration = μ/radius², converted from km/s² to m/s².
What should I check before using the result?
Spherical-body approximation without rotation or local gravitational anomalies.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see NASA: orbits and Kepler’s laws ↗. This is a topic reference, not an external review or endorsement of this tool.
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