{
    "name": "Weight Calculator",
    "url": "https://calculators.geekmidst.com/calculators/weight-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/weight-calculator.md",
    "category": "Science & engineering",
    "description": "Convert a mass in kg or lb into weight (the force of gravity) in newtons, kilogram-force and pound-force on Earth, the Moon and the planets.",
    "summary": "Weight is the force gravity exerts on a mass: W = m × g. Your mass is the same everywhere, but your weight on the Moon is about a sixth of your weight on Earth.",
    "also_called": [
        "Mass to weight converter",
        "Weight on other planets calculator"
    ],
    "applies_to": "Worldwide",
    "last_updated": "2026-10-29",
    "computation": "Results are computed in the visitor’s browser on the HTML page. This API describes the calculator; it does not compute results.",
    "inputs": [
        {
            "name": "mass",
            "label": "Mass",
            "type": "number",
            "default": "70"
        },
        {
            "name": "mass_unit",
            "label": "Mass unit",
            "type": "segmented",
            "default": "kg",
            "options": {
                "kg": "kg",
                "lb": "lb"
            }
        },
        {
            "name": "body",
            "label": "Where",
            "type": "select",
            "default": "earth",
            "options": {
                "earth": "Earth (standard gravity 9.80665 m/s²)",
                "moon": "Moon (1.6 m/s²)",
                "mercury": "Mercury (3.7 m/s²)",
                "venus": "Venus (8.9 m/s²)",
                "mars": "Mars (3.7 m/s²)",
                "jupiter": "Jupiter (23.1 m/s²)",
                "saturn": "Saturn (9.0 m/s²)",
                "uranus": "Uranus (8.7 m/s²)",
                "neptune": "Neptune (11.0 m/s²)",
                "pluto": "Pluto (0.7 m/s²)",
                "custom": "Custom gravity"
            }
        },
        {
            "name": "gravity",
            "label": "Gravitational acceleration",
            "type": "number",
            "default": "9.81",
            "unit": "m/s²",
            "shown_when": {
                "body": "custom"
            }
        }
    ],
    "outputs": [
        {
            "key": "newtons",
            "label": "Weight",
            "format": "number"
        },
        {
            "key": "kgf",
            "label": "Weight in kilogram-force",
            "format": "number"
        },
        {
            "key": "lbf",
            "label": "Weight in pound-force",
            "format": "number"
        },
        {
            "key": "gravity",
            "label": "Gravity used",
            "format": "number"
        },
        {
            "key": "vs_earth",
            "label": "Compared with Earth",
            "format": "percent"
        }
    ],
    "formula": {
        "text": "W = m × g;  kgf = W ÷ 9.80665;  lbf = W ÷ (0.45359237 × 9.80665)",
        "variables": {
            "W": "weight, a force in newtons (N)",
            "m": "mass in kg (1 lb = 0.45359237 kg)",
            "g": "gravitational acceleration at the surface, in m/s²"
        }
    },
    "worked_example": {
        "inputs": {
            "mass": "70",
            "mass_unit": "kg",
            "body": "moon",
            "gravity": "9.81"
        },
        "steps": [
            "On Earth: W = 70 × 9.80665 = 686.47 N.",
            "On the Moon (g = 1.6 m/s²): W = 70 × 1.6 = 112 N.",
            "1.6 ÷ 9.80665 = 16.3% of Earth weight."
        ],
        "result": "A 70 kg person weighs about 686 N on Earth but only 112 N on the Moon, about 16% as much."
    },
    "interpretation": "A bathroom scale shows weight divided by Earth’s gravity, so on the Moon the same scale would read about 11.4 kg for a 70 kg person, even though their mass has not changed.",
    "assumptions": [
        "Planetary values are surface gravity at the equator, rounded to 0.1 m/s², from NASA’s planetary fact sheet. Earth uses standard gravity, 9.80665 m/s²."
    ],
    "limitations": [
        "Real gravity on Earth varies by about 0.5% with latitude and altitude.",
        "For the gas giants, “surface” means the level where atmospheric pressure is 1 bar."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "Is kilogram-force the same as kilogram?",
            "answer": "No. Kilogram is mass; kilogram-force is the weight of 1 kg at standard gravity (9.80665 N). On Earth the numbers match, which is why everyday language mixes them up."
        },
        {
            "question": "Why is my weight on Saturn similar to Earth?",
            "answer": "Saturn is very massive but also very large, so at the level of its cloud tops gravity is about 9.0 m/s², close to Earth’s."
        }
    ],
    "sources": [
        {
            "title": "NASA NSSDCA — Planetary Fact Sheet (metric)",
            "url": "https://nssdc.gsfc.nasa.gov/planetary/factsheet/index.html"
        }
    ],
    "related": [
        {
            "name": "Density Calculator",
            "url": "https://calculators.geekmidst.com/calculators/density-calculator"
        },
        {
            "name": "Speed Calculator",
            "url": "https://calculators.geekmidst.com/calculators/speed-calculator"
        },
        {
            "name": "BMI Calculator",
            "url": "https://calculators.geekmidst.com/calculators/bmi-calculator"
        },
        {
            "name": "Force Calculator (F = ma)",
            "url": "https://calculators.geekmidst.com/calculators/force-mass-acceleration-calculator"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}