Moment of Inertia Calculator
🪐 Gravity & circular motion. Use the Moment of inertia (solid disc) formula to find moment of inertia, mass, radius: pick the value you want, type the others, and the answer updates as you go.
Moment of inertia0.25 kg m²
Pick the ○ next to the value you want to find, fill in the others, and it solves as you type.
What each letter means
| Quantity | Unit |
|---|---|
| Moment of inertia | kg m² |
| Mass | kg |
| Radius | m |
Worked example
Find the moment of inertia when Mass = 2 kg, Radius = 0.5 m.
Using I = 1/2 m r²: Moment of inertia = 0.25 kg m².
Frequently asked questions
What is the formula for Moment of inertia (solid disc)?
I = 1/2 m r².
What do the letters stand for, and what units are used?
Moment of inertia in kg m², Mass in kg, Radius in m.
How do you calculate moment of inertia?
Put the values into I = 1/2 m r². For example, with Mass = 2 kg, Radius = 0.5 m, moment of inertia = 0.25 kg m².
Can I solve for a different value?
Yes. In the calculator above, pick the circle next to any value (moment of inertia, mass, radius) and fill in the others: it rearranges the formula for you.
