{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"planet-weight"},"result":{"entity_type":"calculator","id":"planet-weight","calculator_id":"planet-weight","canonical_url":"https://tttkmbb.com/science/planet-weight","name":"Weight on Other Planets Calculator","title":"Weight on Other Planets Calculator – Your Weight on the Moon, Mars, Jupiter and the Sun (NASA gravity)","category":"science","category_name":"Biology, Earth & Space","tool_name":"calculate_weight_on_planets","featured_mcp_tool":false,"description":"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.","use_when":"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).","inputs":[{"name":"mass_kg","label":"Mass (Earth scale reading)","type":"number","unit":"kg","required":true,"max":1000000000,"exclusive_min":0,"description":"Mass in kilograms, i.e. what a bathroom scale reads on Earth.","example":70},{"name":"body","label":"Body","type":"enum","required":false,"default":"mars","values":[{"value":"mercury","label":"Mercury"},{"value":"venus","label":"Venus"},{"value":"earth","label":"Earth"},{"value":"moon","label":"Moon"},{"value":"mars","label":"Mars"},{"value":"jupiter","label":"Jupiter"},{"value":"saturn","label":"Saturn"},{"value":"uranus","label":"Uranus"},{"value":"neptune","label":"Neptune"},{"value":"pluto","label":"Pluto"},{"value":"sun","label":"Sun"}],"description":"Body for the headline result; the table lists all eleven bodies.","example":"mars"}],"outputs":[{"name":"body_name","label":"Body","type":"string","decimals":4,"description":"Selected body."},{"name":"body_gravity_m_s2","label":"Surface gravity","type":"number","unit":"m/s²","decimals":2,"description":"Surface gravity of the selected body (NASA fact sheet)."},{"name":"weight_on_body_n","label":"Weight on body","type":"number","unit":"N","decimals":2,"description":"mass_kg × g_body."},{"name":"equivalent_mass_feel_kg","label":"Scale reading on body","type":"number","unit":"kg","decimals":2,"description":"What an Earth-calibrated scale would read: mass_kg × g_body / 9.80."},{"name":"gravity_ratio","label":"Gravity relative to Earth","type":"number","decimals":4,"description":"g_body / 9.80."},{"name":"weight_on_earth_n","label":"Weight on Earth","type":"number","unit":"N","decimals":2,"description":"mass_kg × 9.80."},{"name":"table","label":"Scale reading on every body","type":"object","decimals":2,"description":"Equivalent scale reading in kg on each of the eleven bodies, keyed by body."}],"input_schema":{"type":"object","properties":{"mass_kg":{"description":"Mass in kilograms, i.e. what a bathroom scale reads on Earth. Unit: kg.","type":"number","maximum":1000000000,"exclusiveMinimum":0,"examples":[70],"x-unit":"kg"},"body":{"description":"Body for the headline result; the table lists all eleven bodies.","type":"string","enum":["mercury","venus","earth","moon","mars","jupiter","saturn","uranus","neptune","pluto","sun"],"default":"mars","examples":["mars"]}},"additionalProperties":false,"required":["mass_kg"]},"output_schema":{"type":"object","properties":{"body_name":{"description":"Selected body.","type":"string"},"body_gravity_m_s2":{"description":"Surface gravity of the selected body (NASA fact sheet). Unit: m/s².","type":"number","x-unit":"m/s²"},"weight_on_body_n":{"description":"mass_kg × g_body. Unit: N.","type":"number","x-unit":"N"},"equivalent_mass_feel_kg":{"description":"What an Earth-calibrated scale would read: mass_kg × g_body / 9.80. Unit: kg.","type":"number","x-unit":"kg"},"gravity_ratio":{"description":"g_body / 9.80.","type":"number"},"weight_on_earth_n":{"description":"mass_kg × 9.80. Unit: N.","type":"number","x-unit":"N"},"table":{"description":"Equivalent scale reading in kg on each of the eleven bodies, keyed by body.","type":"object"}}},"formula":"weight_N = mass_kg × g_body; equivalent_kg = mass_kg × g_body / 9.80; gravity_ratio = g_body / 9.80","method":"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.","sources":[{"name":"NASA NSSDCA – Planetary Fact Sheet","url":"https://nssdc.gsfc.nasa.gov/planetary/factsheet/","type":"government","retrieved_at":"2026-09-24"},{"name":"NASA NSSDCA – Sun Fact Sheet","url":"https://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html","type":"government","retrieved_at":"2026-09-24"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"70 kg person on Mars","inputs":{"mass_kg":70,"body":"mars"},"expected":{"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}},"url":"https://tttkmbb.com/api/v1/calculate/planet-weight?mass_kg=70&body=mars"},{"name":"100 kg on the Moon","inputs":{"mass_kg":100,"body":"moon"},"expected":{"weight_on_body_n":162,"equivalent_mass_feel_kg":16.53,"gravity_ratio":0.1653},"url":"https://tttkmbb.com/api/v1/calculate/planet-weight?mass_kg=100&body=moon"}],"faq":[{"q":"Does my mass change on other planets?","a":"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."},{"q":"Why 9.80 and not 9.81 for Earth?","a":"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."},{"q":"How can the Sun or Jupiter have a surface gravity?","a":"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."}],"tags":["weight on other planets","weight on mars","weight on the moon","surface gravity","planet gravity","weight on jupiter"],"related":[{"calculator_id":"gravitational-force","reason":"Newton's law of gravitation for two arbitrary masses."},{"calculator_id":"newtons-second-law","reason":"Weight as mass × acceleration."},{"calculator_id":"escape-velocity","reason":"Escape and orbital speeds of the same bodies."}],"links":{"html":"https://tttkmbb.com/science/planet-weight","markdown":"https://tttkmbb.com/science/planet-weight.md","json":"https://tttkmbb.com/science/planet-weight.json","api":"https://tttkmbb.com/api/v1/calculate/planet-weight","schema":"https://tttkmbb.com/api/v1/calculators/planet-weight","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T03:45:39Z","next_actions":[{"tool":"run_calculator","calculator_id":"planet-weight","reason":"Run Weight on Other Planets Calculator with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/science/planet-weight.md"}}