← All calculators
Mechanics
Rectangular Section Properties
Enter values in the stated units. Example inputs are provided to help you explore the method.
Results
Your results will appear here after calculation. Changing an input clears the previous result.
Method & assumptions
- Concentric rectangular opening with sharp corners. Set both inner dimensions to zero for solid. A = bh − bi hi; Ix = (b h³ − bi hi³)/12; Iy = (h b³ − hi bi³)/12. Wall thickness may differ horizontally and vertically.
- All dimensions in metres. Axes pass through the centroid: x horizontal, y vertical. Centroid coordinates are measured from the bottom-left of the outer bounding box. These are area properties, not mass moments of inertia.
- Sx = Ix/(outer height/2), Sy = Iy/(outer width/2); rx = √(Ix/A), ry = √(Iy/A). The section modulus has dimensions of length cubed, but is not a volume of material.
- Polar area moment Jp = Ix + Iy. It equals the Saint-Venant torsion constant for a circular solid/annulus, not for a rectangle. No rounded corners, eccentric void, strength rating, local buckling or design-code check is included.