Basic formula
For a simply supported beam with a full-span uniformly distributed load, maximum M = wL² ÷ 8.
Worked example
For w = 10 kN/m and L = 5 m, M = 10 × 25 ÷ 8 = 31.25 kN·m.
How to use the calculator
Enter UDL and span in the units shown. Confirm that the support and loading assumptions match the formula.
Why design is more complex
Real design can require load combinations, self-weight, point loads, shear, deflection, reinforcement and code checks.
Safety note
Do not use this preliminary result as a final construction design.
Use the Beam Bending Moment Calculator
Enter your project values and get a quick preliminary calculation.
Engineering note: Results are intended for preliminary estimation, planning and learning. Verify measurements, drawings, specifications, current rates, applicable standards and site conditions before construction or safety-critical decisions.
Frequently Asked Questions
What is the formula?
For the stated idealized case, maximum moment is wL²/8.
What units are used?
Commonly kN/m for load and metres for span.
Does it work for every beam?
No; it applies to the stated support and loading condition.
Can it design reinforcement?
No.