Angular Momentum Calculator
Find angular momentum and rotational kinetic energy from a known inertia and angular speed. The tool shows the method and key assumptions so you can inspect how the input values lead to the estimate.
How to use this calculator
- Enter moment of inertia (kg·m²) using the unit and definition shown beside the input.
- Enter angular speed (rad/s) using the unit and definition shown beside the input.
- Check that all values refer to the same time period and scenario.
- Review the outputs alongside the assumptions before using them in a decision.
Formula and assumptions
Angular momentum L=Iω; rotational kinetic energy E=½Iω².
- Uses a fixed-axis rigid-body model and the moment of inertia supplied by you. It does not account for changing inertia, external torques or multi-axis rotation.
- The estimate is calculated from values you enter. It does not connect to external accounts, obtain live prices, or validate local regulations or engineering specifications.
Worked examples
Worked example
For I=0.85 kg·m² and ω=18 rad/s, L=15.3 kg·m²/s.
Enter inertia in kg·m² and angular speed in rad/s.
Use the appropriate inertia model and reference axis for the object.
Understanding the result
Uses a fixed-axis rigid-body model and the moment of inertia supplied by you. It does not account for changing inertia, external torques or multi-axis rotation.
Change one input at a time to see how sensitive the output is to that assumption.
Important notes
Uses a fixed-axis rigid-body model and the moment of inertia supplied by you. It does not account for changing inertia, external torques or multi-axis rotation.
Frequently asked questions
What formula does the Angular Momentum Calculator use?
Angular momentum L=Iω; rotational kinetic energy E=½Iω².
What should I verify before relying on the result?
Uses a fixed-axis rigid-body model and the moment of inertia supplied by you. It does not account for changing inertia, external torques or multi-axis rotation.
Can I compare different scenarios?
Yes. Change one assumption at a time, keep units and definitions consistent, and save the inputs used for each comparison.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.