Weight Calculator – Mass, Gravity, Planets And Liquid Loads
This weight calculator collects several small physics tools into one page. You can compute weight directly from mass and gravity, estimate weight from density and volume, convert weight units, explore how body weight changes across the Solar System, approximate the weight of solid objects by shape and calculate the weight of liquid stored in tanks.
Weight, Mass And Gravity
Weight is the force created when gravity acts on mass. The core relationship is:
W = m × g
where W is weight (force), m is mass and g is the local gravitational acceleration. Mass is the same everywhere, but weight changes with g. On the Moon, g is weaker than on Earth, so the same mass weighs less.
Density, Volume And Load Planning
Many engineering and storage questions start from volume instead of mass. If you know a material’s density and the volume you are filling, you can estimate mass and then weight. This is useful for water tanks, fuel tanks, concrete pours and bulk materials. The density-based tab and the tank tab work well together with the dedicated Density Calculator when you need more detail on material properties.
Body Weight On Different Planets
The planetary tab keeps your mass fixed and changes gravity to show how your weight would change on Mercury, Venus, Earth, the Moon, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. It is a helpful way to build intuition for gravity while also engaging students and curious readers.
Shapes, Tanks And Real-World Objects
The shape tab estimates volume of simple geometries such as cubes, blocks, cylinders and spheres, then combines that with density and gravity to return mass and weight. The tank tab focuses specifically on rectangular and vertical cylindrical tanks with a fill height, which is common in storage and process work. Both tools pair well with the Mass Calculator when you also care about mass totals, not just weight.
Mass & Weight Calculator
Frequently Asked Questions
Learn the difference between mass and weight, why Newtons are used, and how planetary gravity affects calculations.
Mass measures how much matter an object contains and is usually given in kilograms. Weight is the force of gravity acting on that mass and is measured in Newtons or pound-force. Mass stays the same everywhere in the universe, while weight changes depending on the strength of the gravitational field.
In everyday life, people often use “kilograms” to describe weight even though kilograms measure mass. Scales respond to force, not mass. In physics and engineering, weight is treated strictly as a force, so it is expressed in Newtons. This keeps formulas consistent across planets and different gravity levels.
The gravity values included for planets and moons are rounded standard values from commonly used references. They are accurate enough for learning, demonstrations, and basic design checks. For spacecraft, scientific missions or precision engineering, more detailed gravity models should be used.
No. This calculator is intended for quick estimates and educational use. Structural design, safety-critical engineering, and regulated projects require formal design methods, properly validated models, and review by qualified professionals.