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Weight on Other Planets Calculator

Converts a mass (the scale reading on Earth) into the weight in newtons and the equivalent scale reading on Mercury, Venus, Earth, the Moon, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto and the Sun, using surface gravity values from the NASA planetary fact sheets.

When to use

You want to know how much a person or object would weigh on another planet, the Moon or the Sun, or the gravity ratio between a body and Earth.

Do not use when: You need the gravitational force between two arbitrary masses (use gravitational-force) or the weight at altitude or in orbit (use escape-velocity for orbital speeds).

Formula

weight_N = mass_kg × g_body; equivalent_kg = mass_kg × g_body / 9.80; gravity_ratio = g_body / 9.80

Surface gravity in m/s² from the NASA planetary fact sheets (values without the centrifugal effect of rotation): Mercury 3.7, Venus 8.87, Earth 9.80, Moon 1.62, Mars 3.71, Jupiter 24.79, Saturn 10.44, Uranus 8.87, Neptune 11.15, Pluto 0.62, Sun 274. Gas giants and the Sun have no solid surface; their value refers to the 1-bar level or the visible photosphere.

Inputs

Parameter	Type	Unit	Required	Description
`mass_kg`	number	kg	yes	Mass in kilograms, i.e. what a bathroom scale reads on Earth. Range: > 0, ≤ 1000000000
`body`	enum: mercury \| venus \| earth \| moon \| mars \| jupiter \| saturn \| uranus \| neptune \| pluto \| sun		default mars	Body for the headline result; the table lists all eleven bodies.

Outputs

Output	Type	Unit	Description
`body_name`	string		Selected body.
`body_gravity_m_s2`	number	m/s²	Surface gravity of the selected body (NASA fact sheet).
`weight_on_body_n`	number	N	mass_kg × g_body.
`equivalent_mass_feel_kg`	number	kg	What an Earth-calibrated scale would read: mass_kg × g_body / 9.80.
`gravity_ratio`	number		g_body / 9.80.
`weight_on_earth_n`	number	N	mass_kg × 9.80.
`table`	object		Equivalent scale reading in kg on each of the eleven bodies, keyed by body.

Example

70 kg person on Mars: {"mass_kg":70,"body":"mars"} → {"weight_on_body_n":259.7,"equivalent_mass_feel_kg":26.5,"gravity_ratio":0.3786,"weight_on_earth_n":686,"table":{"jupiter":177.07,"moon":11.57}}

100 kg on the Moon: {"mass_kg":100,"body":"moon"} → {"weight_on_body_n":162,"equivalent_mass_feel_kg":16.53,"gravity_ratio":0.1653}

GET https://tttkmbb.com/api/v1/calculate/planet-weight?mass_kg=70&body=mars

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/planet-weight (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/planet-weight · Markdown: https://tttkmbb.com/science/planet-weight.md · JSON definition: https://tttkmbb.com/science/planet-weight.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="planet-weight"
OpenAPI operationId: calculate_weight_on_planets
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

NASA NSSDCA – Planetary Fact Sheet (government)
NASA NSSDCA – Sun Fact Sheet (government)

FAQ

Does my mass change on other planets?

No. Mass is the same everywhere; weight (the force of gravity, in newtons) changes with the local gravity, and a scale calibrated on Earth shows mass × g_body / 9.80.

Why 9.80 and not 9.81 for Earth?

The NASA fact sheet lists 9.80 m/s²; standard gravity is 9.80665 m/s² and actual values range from about 9.78 at the equator to 9.83 at the poles.

How can the Sun or Jupiter have a surface gravity?

It is computed at a reference level: the 1-bar pressure level for the gas giants and the photosphere for the Sun, from GM / R² without rotation.

Related calculators

Gravitational Force Calculator — Newton's law of gravitation for two arbitrary masses.
Force Calculator — Weight as mass × acceleration.
Escape Velocity Calculator — Escape and orbital speeds of the same bodies.