Gravitational force tool

Weight Calculator

Calculate weight, mass, or gravitational acceleration from two known values using W = m × g.

Enter two known values

Solve a weight problem

Free tool
N

This is the value being calculated.

kg

Amount of matter in the object.

m/s²

Local gravitational acceleration.

Use kilograms for mass, meters per second squared for gravity, and newtons for weight. Standard Earth gravity is 9.80665 m/s².

Try an example:

Your weight result will appear here

Choose the missing variable and enter the other two known values.

Calculator guide

How this calculator works

Weight Calculator determines the gravitational force acting on an object from its mass and gravitational acceleration. It helps physics students, engineers, and laboratory users calculate weight accurately using Newtonian mechanics principles.

Formula explanation

Weight represents gravitational force acting on an object and is calculated using W = mg.

Formula

Weight Force = m × g

Worked example

Example: An object's weight changes when it moves between environments with different gravity.

Assumptions

  • Mass measurements are accurate.
  • The selected gravitational acceleration represents the environment being analyzed.
  • Units remain compatible throughout the calculation.

Examples

  • Example: Calculate an object's weight on Earth using mass and standard gravitational acceleration.
  • Example: Scientists compare weight values on different planets by using different gravitational acceleration values.

Common mistakes

  • Confusing mass and weight.
  • Using incorrect gravity values.
  • Ignoring unit conversions.

Variables

  • Object mass
  • Gravitational acceleration
  • Weight force
  • Planetary gravity value
  • Measurement units

Limitations

  • Results depend on the accuracy of the selected gravitational acceleration.
  • Real measurements may vary because of environmental and instrument factors.

Scientific references

  • OpenStax University Physics: Forces and Newton's Laws
  • Classical mechanics principles
  • Scientific measurement references

Content review

Reviewed by: ScienceCalcHub Physics Review Team | Last reviewed: 2026-08-30

Applications

  • Physics education
  • Engineering force calculations
  • Laboratory measurements
  • Scientific mechanics analysis

Frequently asked questions

How is weight calculated?

Weight is calculated by multiplying an object's mass by gravitational acceleration using the formula W = m × g.

What is the difference between mass and weight?

Mass describes the amount of matter in an object, while weight describes the gravitational force acting on that mass.

Why does weight change on different planets?

Weight changes because gravitational acceleration differs between planets, while the object's mass remains constant.

Accuracy and transparency

Created and maintained by our editorial team

This physics calculator is maintained by the ScienceCalcHub Editorial Team. Its calculation logic is tested with representative inputs, while the supporting guidance is checked for formula clarity, units, assumptions, and common mistakes.

Written by
ScienceCalcHub Editorial Team
Reviewed by
ScienceCalcHub Scientific Review Team
Review standard
Formula accuracy, units, examples, and educational clarity

Learn more about our formula-review and correction process, explore our calculation methodology, or view our scientific references.

  • Calculation logic tested
  • Variables and units explained
  • Assumptions stated clearly
  • Corrections handled transparently

Physics overview

What is weight?

Weight is the gravitational force acting on an object. It depends on both the object's mass and the local gravitational acceleration.

An object keeps the same mass when moved between planets or moons, but its weight changes because gravitational acceleration is different.

Formula

Weight formula

WeightW = m × g

  • W is weight in newtons.
  • m is mass in kilograms.
  • g is gravitational acceleration in meters per second squared.

Worked example

Calculate the weight of a 10 kg object on Earth

  1. Write the formula: W = m × g.
  2. Substitute the values: W = 10 × 9.80665.
  3. Calculate the result: W = 98.0665 N.

Gravity comparison

Calculate weight on the Moon

A 60 kg person has a mass of 60 kg on both Earth and the Moon. Using lunar gravity of approximately 1.62 m/s²:

Lunar weightW = 60 × 1.62 = 97.2 N

The person's mass remains 60 kg, but the gravitational force acting on that mass is much smaller.

Rearranged equations

Solve for mass or gravity

Mass

m = W ÷ g

Divide weight by gravitational acceleration.

Gravity

g = W ÷ m

Divide weight by a positive mass.

Important distinction

Mass is not the same as weight

Mass

Measured in kilograms

Mass describes the amount of matter in an object and does not depend on location.

Weight

Measured in newtons

Weight is a force and changes when gravitational acceleration changes.

Standard gravity

Which Earth gravity value should you use?

Standard gravitational acceleration is defined as 9.80665 m/s². Many school and laboratory problems round this value to 9.81 m/s² or 9.8 m/s².

Use the precision requested by your assignment or experiment. Do not round intermediate results too early when a precise final answer is required.

Relationship to force

Weight is a specific type of force

Newton's second law states that force equals mass multiplied by acceleration. For weight calculations, the acceleration is specifically gravitational acceleration.

General forceF = m × a

Gravitational forceW = m × g

Units

Use consistent SI units

  • Enter mass in kilograms.
  • Enter gravity in meters per second squared.
  • Report weight in newtons.
  • Convert grams to kilograms before calculating.

One newton1 N = 1 kg·m/s²

Assumptions

What the calculation represents

  • Mass and gravity must be greater than zero.
  • Gravity is treated as constant for the calculation.
  • The calculator uses SI units without automatic unit conversion.
  • The result represents gravitational force, not apparent weight caused by additional acceleration.

Related tools

Use the Force Calculator to calculate general force, mass, or acceleration using Newton's second law.

Use the Acceleration Due to Gravity Calculator to estimate gravity from a celestial body's mass and radius.

Use the Gravitational Potential Energy Calculator to calculate energy from mass, gravity, and height.

Questions and answers

Calculator FAQ

How is weight calculated?

Weight is calculated by multiplying an object's mass by gravitational acceleration using the formula W = m × g.

What is the difference between mass and weight?

Mass describes the amount of matter in an object, while weight describes the gravitational force acting on that mass.

Why does weight change on different planets?

Weight changes because gravitational acceleration differs between planets, while the object's mass remains constant.