Calculate section modulus, moment of inertia, bending stress, required section modulus, and simplified bending capacity. Use this section modulus calculator for rectangular beams, round bars, solid shafts, hollow tubes, rectangular tubes, pipe sections, and preliminary beam sizing.
Shape properties:
The calculator estimates moment of inertia and section modulus from the selected cross-section shape.
Required section modulus:
The calculator divides bending moment by allowable bending stress to estimate the minimum required section modulus.
Bending stress:
The calculator converts moment to inch-pounds and divides by section modulus to estimate bending stress.
Capacity check:
The calculator multiplies section modulus by allowable stress to estimate simplified moment capacity.
A section modulus calculator helps compare member shapes and sizes for bending strength before selecting a beam, joist, tube, pipe, or structural section.
It can help compare moment of inertia, section modulus, bending stress, required section modulus, moment capacity, and simplified utilization.
Your result shows estimated moment of inertia, extreme fiber distance, section modulus, required section modulus, bending stress, allowable bending stress, moment capacity, and simplified bending utilization. These are preliminary planning estimates only.
Section modulus is a cross-section property used to estimate bending stress. It equals moment of inertia divided by the distance from the neutral axis to the outermost fiber.
Convert the bending moment to inch-pounds, then divide by allowable bending stress in PSI. The result is required section modulus in cubic inches.
For a rectangular beam, section modulus equals b × d² ÷ 6, so increasing depth has a squared effect on section modulus.
No. This calculator estimates section modulus and simplified bending stress only. Final design should also check shear, deflection, bearing, bracing, connections, load combinations, material grade, and local code requirements.