Beam Bending Stress Calculator

Calculate nominal bending stress from moment and section modulus.

Live concept view — geometry scales with the entered design condition.

PRELIMINARY RESULT

Nominal bending stress100.00 MPa

Calculation detail

Formula: σ = M / Z

Bending moment is converted to N·mm and divided by the elastic section modulus.

Beam Bending Stress Calculator: operating questions

Does acceptable bending stress mean the beam is adequate?

No. Shear, deflection, vibration, lateral-torsional buckling, local buckling, connections and code load combinations can govern independently.

Which section modulus should be entered?

Use the elastic section modulus about the actual bending axis and orientation, adjusted for the net or effective section when required by the governing method.

Where does the maximum moment come from?

It must be derived from the actual support conditions, load positions and governing load combination. This calculator does not determine reactions or the moment diagram.

Illustrative input values and units
Parameter	Unit	Example
Maximum bending moment	kN·m	25
Section modulus	mm³	250000

Technical verification

Equation checked: 2026-09-15 · Units checked: 2026-09-15 · Independent numerical case: Pass

Source basis: TEXTBOOK — MIT OpenCourseWare, Stresses in Beams, equation 7

Unit basis: kN·m × 10⁶ → N·mm; N/mm² = MPa

Independent example: 25 kN·m / 250000 mm³ gives 100 MPa.

Scope: Elastic flexure only; no buckling, plasticity, fatigue, stress concentration or code acceptance.

Technical verification is not professional engineering certification and does not approve a specific real-world design.