Moments of Inertia of Common Shapes


rectangle

x' =
1
12
bh3
y' =
1
12
b3h
Ix =
1
3
bh3
Iy =
1
3
b3h
JC =
1
12
bh(b2 + h2)
triangle

x' =
1
36
bh3
y' =
1
12
bh3
circle

x = y =
1
4
πr4
JO =
1
2
πr4
semicircle

Ix = Iy =
1
8
πr2
JO =
1
4
πr4
quarter circle

Ix = Iy =
1
16
πr4
JO = Iz =
1
8
πr4
ellipse

x =
1
4
πab3
y =
1
4
πa3b
JO =
1
4
πab(a2 + b2)