Engineering & mechanics
Rectangle section properties
Find centroidal area moments and elastic section moduli for a rectangular section.
A clear answer. Here’s how.
For an unperforated rectangle, Ix=b h³/12 and Iy=h b³/12 about centroidal axes. Elastic section moduli are Ix/(h/2) and Iy/(b/2). The polar area moment is Ix+Iy; it is not the Saint-Venant torsion constant for a rectangular bar. Reports area too. Input dimensions are millimetres; this does not check loads or material strength.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Section width b (mm)
- 40
- Section height h (mm)
- 80
Example result
- Area (mm²)
- 3,200
- Centroidal Ix (mm⁴)
- 1,706,666.66667
- Centroidal Iy (mm⁴)
- 426,666.666667
- Elastic section modulus about X (mm³)
- 42,666.6666667
- Elastic section modulus about Y (mm³)
- 21,333.3333333
- Polar area moment Ix + Iy (mm⁴)
- 2,133,333.33333