Planet Weight Calculator
Calculate your weight on planets, the Moon, or a custom world using local gravitational acceleration, with written solution steps and a visual planet diagram.
Your Weight on Mars
Step-by-Step Planet Weight Solution
Step 1: Use the weight formula
Weight is the gravitational force acting on an object's mass.
Step 2: Substitute your mass and local gravity
Step 3: Calculate your weight on Mars
Planet Weight Calculator
This Planet Weight Calculator shows how much you would weigh on Mercury, Venus, Earth, the Moon, Mars, Jupiter, Saturn, Uranus, Neptune, or a custom world. Enter your mass in kilograms, choose a planet, and the calculator applies that world's gravitational acceleration. It returns your weight in newtons, compares it with your Earth weight, and displays a visual diagram of the chosen planet.
The tool is useful for science homework, astronomy projects, classroom demonstrations, and simple curiosity about other planets. It also includes written steps showing the weight formula, the values substituted, and the final result. You can use a custom gravity value to calculate weight on an asteroid, fictional planet, space station, or any location where a known gravitational field strength is available.
Weight Formula: W = m x g
Weight is calculated with W = m x g. W is weight in newtons, m is mass in kilograms, and g is the local gravitational acceleration in metres per second squared. The same equation can also be written as W = mg. A newton is the SI unit of force. Because gravity changes from one world to another, weight changes even though a person's mass stays exactly the same.
For example, a person with a mass of 70 kg has a mass of 70 kg on Earth, Mars, and the Moon. On Earth, their weight is about 687 N. On Mars, where gravity is lower, their weight is about 260 N. On Jupiter, where gravity is stronger, their weight is about 1,735 N. This is why the calculator asks for mass rather than Earth weight.
Mass and Weight Are Not the Same
Mass measures how much matter an object contains. It is measured in kilograms and does not change when you travel. Weight is a force caused by gravity pulling on that mass. It is measured in newtons and changes whenever local gravity changes. In everyday conversation, people often say that they weigh 70 kg, but kilograms technically describe mass rather than weight.
A bathroom scale is calibrated to display a mass value based on Earth's gravity. If you took the same scale to another planet, its reading would change because the force on the scale would be different. The Planet Weight Calculator gives the scientific force value in newtons and also shows the percentage of your Earth weight, making the comparison straightforward.
Your Weight on Each Planet
Mercury has gravity of about 3.70 m/s squared, so you would weigh roughly 38 percent of your Earth weight. Venus has gravity close to Earth at 8.87 m/s squared. Mars has about 38 percent of Earth gravity, while the Moon has only about 16.5 percent. You could jump higher and lift objects more easily on these lower-gravity worlds, although your mass and inertia would not change.
Jupiter has a gravity of about 24.79 m/s squared, approximately 2.53 times Earth gravity. Saturn's gravity is slightly stronger than Earth's despite its very large size, while Uranus and Neptune have values close to Earth. These values are standard approximate surface gravities. A giant planet has no solid surface in the same sense as Earth, so a reference level is used for comparison.
How to Use This Weight on Planets Calculator
First enter your mass in kilograms. If you know only your Earth weight in newtons, divide it by 9.80665 to estimate your mass. Next choose a planet or the Moon from the menu. The calculator instantly multiplies your mass by that world's gravity. The result panel gives the weight in newtons, Earth equivalent, gravity used, and percentage of Earth gravity.
Choose Custom gravity when you want to use a value not listed in the menu. This works well for an exoplanet exercise, a moon, or a fictional setting. Use metres per second squared for the custom gravity value. The live solution shows Step 1, Step 2, and Step 3 so you can follow W = m x g rather than treating the result as a black box.
Why Planetary Gravity Is Different
Surface gravity depends mainly on a body's mass and radius. A more massive object tends to have stronger gravity, but a larger radius puts the surface farther from its centre and can reduce the strength. Newton's gravity formula is g = GM/r squared, where G is the gravitational constant, M is mass, and r is the distance from the centre.
This explains why gravity does not depend on mass alone. Jupiter is much more massive than Earth and has stronger gravity, but its enormous radius reduces the surface value compared with what mass alone might suggest. Mars has less mass and a smaller radius, resulting in much lower gravity. The Planet Weight Calculator uses published approximate gravity values for easy comparison.
Weight, Gravity, and Daily Movement
Lower gravity changes the force needed to support your body, so you would weigh less and could jump higher. However, your mass remains unchanged, so moving your limbs or stopping after motion still requires the same inertia-related effort. Walking and balance would feel unfamiliar because your body would spend more time in the air with every step.
In higher gravity, your weight would increase and everyday movement would require more muscular force. Carrying equipment, standing, and climbing would be more demanding. Long-term effects on the human body are an active topic in space science. This simple calculator describes the immediate force comparison; it does not model atmosphere, health effects, or a planet's rotation.
Earth Weight Compared with Planet Weight
Earth is a useful baseline because its standard gravitational acceleration is 9.80665 m/s squared. Divide another world's gravity by this value to find the fraction of Earth weight. Multiply by 100 to express it as a percentage. For instance, Mars gravity of 3.71 m/s squared is about 37.8 percent of Earth gravity. A 70 kg person's Mars weight is therefore about 37.8 percent of their Earth weight in newtons.
This comparison is not a conversion from kilograms to kilograms. It is a force comparison. If a scale on Earth displays 70 kg, it is interpreting the gravitational force as mass under Earth conditions. A correctly calibrated scale on Mars would display a different number unless it was specifically programmed to report the person's mass rather than the local force. The calculator avoids this ambiguity by showing newtons first.
Using Custom Gravity for Moons and Exoplanets
The custom gravity setting extends the calculator beyond the Solar System planets. Use it for a known moon, dwarf planet, asteroid, exoplanet, fictional world, or a classroom problem. Enter the local gravitational acceleration in m/s squared, then the calculator applies the same weight equation. This is often the simplest approach when a question gives g directly rather than mass and radius.
If a problem instead gives a world's mass and radius, first calculate its surface gravity using g = GM/r squared, then enter that result in the custom field. Be careful to use radius in metres and mass in kilograms. This two-stage method connects the Planet Weight Calculator with Newton's universal gravitation law and lets you create a consistent estimate for virtually any spherical astronomical body.
Common Planet Weight Calculation Mistakes
The most common mistake is typing a body weight value in kilograms into the mass field without understanding what the value represents. In everyday contexts, a value such as 70 kg is generally treated as mass, so it is suitable for this calculator. If you have a force measured in newtons instead, divide by Earth gravity to find mass before comparing worlds. Do not multiply an Earth weight in newtons by a second gravity value.
Another mistake is mixing up newtons and kilograms or assuming that a person loses matter when their planetary weight changes. Remember: mass remains constant, gravity varies, and weight is the product of both. Use the displayed gravity value and written substitution steps to check the calculation. Rounded planetary gravity values are suitable for education and comparison, but actual local gravity can vary slightly with latitude, altitude, rotation, and terrain.
Planet Weight Calculator FAQ
Can I calculate my weight on the Moon? Yes. Select Moon and enter your mass; its gravity is about 1.62 m/s squared. Why is my weight on Mars lower? Mars has weaker surface gravity than Earth. Does my mass change on another planet? No. Only your weight changes. What unit is weight measured in? In physics, weight is measured in newtons.
For meaningful results, enter a positive mass in kilograms and remember that the values are approximate standard gravities. The Planet Weight Calculator combines the correct physics formula, a planet comparison, worked steps, and an attractive diagram to make gravitational weight easy to understand. It is ideal for comparing Solar System worlds, checking classroom answers, and visualizing the difference between mass, weight, and gravity.
Frequently Asked Questions
How do I calculate my weight on another planet?
Multiply your mass in kilograms by the planet's gravity in m/s squared.
Do I have less mass on the Moon?
No. Your mass stays the same; your weight is lower because Moon gravity is weaker.
Which planet would I weigh the most on?
Of the planets listed, Jupiter has the strongest standard gravity.
Why is weight measured in newtons?
Weight is a gravitational force, and the SI unit of force is the newton.