Is potential energy absolute?
No — only differences in PE matter. You choose a reference level (often the ground) where PE = 0.
Gravitational Potential Energy Calculator
PE = mgh
Calculate gravitational potential energy near Earth. PE = mgh — energy of position in a gravitational field.
Calculate
Enter values above to calculate
How it calculates
1
PE = m × g × h
2
m in kg, g in m/s², h in metres (relative to reference level)
3
Result in joules
Formula
PE = mgh
Variable Table
| Symbol | Quantity | SI Unit |
|---|---|---|
| PE | Gravitational potential energy | J |
| m | Mass | kg |
| g | Gravitational acceleration | m/s² |
| h | Height above reference | m |
→ Conservation of Energy article
How to Use This Calculator
This gravitational potential energy calculator is built for quick physics checks and worked-problem review. Enter values in the units shown beside each input, then compare the result with the formula and variable table before using it in a longer solution. The calculator does the arithmetic, but the physics still depends on choosing a model that matches the situation.
Start by identifying the system, the known quantities, and the quantity you want to find. If a value is given in a non-SI unit, convert it before substitution. A correct numerical answer with mixed units can still be physically wrong, especially when squared units, inverse seconds, charges, temperatures, or distances are involved.
Assumptions and Limits
The formula PE = mgh is a model, not a universal description of every possible case. It assumes the quantities in the variable table are the relevant quantities for the problem and that hidden effects are either negligible or already included in the inputs. If friction, drag, relativistic speeds, changing fields, non-constant temperature, or geometry-specific effects matter, check whether a more complete model is needed.
Use the result as a magnitude and units check. Ask whether the answer has the right sign, whether it grows or shrinks when an input changes, and whether the limiting cases make sense. Setting an input to zero, doubling a quantity, or using a very large value is often enough to catch a formula choice or unit mistake before it reaches a final answer.
Worked Example
A 10 kg box lifted 5 m (g = 9.81). Find PE gained.
Step 1: PE = mgh
Step 2: PE = 10 × 9.81 × 5
Answer: PE = 490.5 J
Common Mistakes
- PE = mgh only applies near Earth's surface where g is roughly constant
- For large distances use PE = −GMm/r
- h is measured relative to a chosen reference level (PE is relative, not absolute)
Related
Frequently Asked Questions
When does PE = mgh fail?
When height is large compared to Earth's radius, g varies. Then use PE = −GMm/r.