Potential Energy Calculator

Use PE = mgh with common mass and height units and compare joules, kilojoules, watt-hours, and foot-pounds.

Mass

Height change

Gravity

—J

—kJ

—Wh

—ft·lbf

—PE = mgh

These are idealized classical-physics calculations. Real systems can differ because of air resistance, friction, deformation, measurement uncertainty, non-constant forces, or other effects not included in the selected model.

Physics model preflight

Check the governing model before trusting the number

near-surface uniform gravity

ΔU = mgΔh

Reading the current native inputs…

Mass is non-negative and g positive. Height change may be positive or negative relative to the chosen reference. This is an idealized educational model: unit consistency and valid inputs do not guarantee that omitted effects are negligible in a real system.

State the model before trusting the number

Classical formulas are only as good as their assumptions and units. Air resistance, damping, deformation, non-constant forces and measurement uncertainty are not silently invented when the selected model does not include them.

Governing physics model

ΔU = mgΔh — near-surface uniform gravity.

How to verify the result

Divide ΔU by mg to recover the entered signed height change. Lowering an object should produce a negative energy change.

Domain and assumption boundary

Mass is non-negative and g positive. Height change may be positive or negative relative to the chosen reference. The calculator does not silently add drag, damping, deformation, varying fields, relativistic effects, measurement uncertainty, or geometry that the selected model does not contain.

Practical guide and verification

Use the tool first, then apply these checks to verify the inputs, interpret the result, and hand it off without displacing the primary workflow.

State the reference height before interpreting the energy

Gravitational potential energy near Earth is measured relative to a chosen zero height. The same object can have different numerical potential energy under different reference choices while physical energy changes remain consistent. Record what height zero represents when the result will be compared with another calculation.

Keep mass, height, and gravity units consistent

The familiar mgh form yields joules when mass is in kilograms, height in meters, and gravitational acceleration in meters per second squared. Convert units before interpreting the result and check the displayed unit labels. A pound-force or feet input cannot be mixed into the SI formula without conversion.

Use the near-surface model only where constant g is reasonable

The mgh approximation treats gravitational acceleration as constant. That is appropriate for many everyday height changes near a planetary surface, but it is not the general gravitational potential formula for very large altitude changes or orbital problems. Use a gravitational parameter model when g changes materially with distance.

Cross-check energy changes with direction

Raising a mass by a positive height change increases gravitational potential energy; lowering it decreases the chosen potential-energy value by the same magnitude under constant g. If the sign or scale looks surprising, recheck the reference height and units before adding the result to a work or energy-conservation analysis.