# Second Moment of Area of a Circle

Written by Jerry Ratzlaff on . Posted in Plane Geometry

## Second Moment of Area of a Circle formulas

 $$\large{ I_{x} = \frac { \pi \; r^4}{ 4 } }$$ $$\large{ I_{y} = \frac { \pi \; r^4}{ 4 } }$$ $$\large{ I_{x1} = \frac { 5 \; \pi \; r^4}{ 4 } }$$ $$\large{ I_{y1} = \frac {5 \; \pi \; r^4}{ 4 } }$$

### Where:

 Units English Metric $$\large{ I }$$ = moment of inertia $$\large{ in^4 }$$ $$\large{ mm^4 }$$ $$\large{ \pi }$$ = Pi $$\large{3.141 592 653 ...}$$ $$\large{ r }$$ = radius $$\large{ in }$$ $$\large{mm }$$