Physics
Instant, private, and free
Flywheel Energy Storage Calculator.
Calculate rotational energy stored in a flywheel.
Set your values
Results update as you type.
Educational SI model using the assumptions stated above; verify engineering and safety decisions independently.
Use Cases
Engineering design and analysis
Engineers can quickly estimate the energy storage capacity of a flywheel for applications like regenerative braking or grid stabilization, helping in preliminary design decisions.
Example: A flywheel with I = 10 kg·m² spinning at 300 rad/s stores 450,000 J.
Physics education and homework
Students can verify their manual calculations of rotational kinetic energy, reinforcing the relationship between inertia, angular velocity, and stored energy.
Example: Check a problem where I = 2 kg·m² and ω = 50 rad/s gives 2,500 J.
Frequently Asked Questions
- What does the flywheel energy storage calculator do?
- This calculator computes the rotational kinetic energy stored in a flywheel. You input the moment of inertia (in kg·m²) and the angular velocity (in rad/s), and it outputs the energy in joules using the formula E = 0.5 * I * ω².
- What units should I use for moment of inertia and angular velocity?
- Use kilogram-square meters (kg·m²) for moment of inertia and radians per second (rad/s) for angular velocity. The result will be in joules (J). Ensure your inputs are in these units for accurate calculations.
- Can I use this calculator for any flywheel design?
- Yes, as long as you know the flywheel's moment of inertia and its angular velocity. The calculator works for any flywheel, whether it's a solid disk, rim, or other shape, provided you have the correct moment of inertia value.
Tips & Common Mistakes
Tips
- Ensure your angular velocity is in rad/s, not rpm. To convert rpm to rad/s, multiply by 2π/60.
- Double-check your moment of inertia value; it depends on the flywheel's mass distribution and shape.
- For a solid disk, I = 0.5 * m * r²; for a rim, I = m * r². Use the correct formula for your design.
- Remember that energy scales with the square of angular velocity, so doubling speed quadruples stored energy.
Common Mistakes to Avoid
- Using angular velocity in revolutions per minute (rpm) without converting to rad/s, leading to incorrect results.
- Confusing moment of inertia with mass; they are different properties. Moment of inertia depends on mass distribution.
- Forgetting to square the angular velocity in the formula, resulting in an energy value that is too low.
Last updated: August 13, 2026