How to use the Euler buckling load calculator
This page finds the axial load at which a compression member starts to bow out. Enter the modulus of elasticity, the member length and the end condition, and describe the section either by rectangular dimensions or by its moment of inertia. The result shows the effective length and the Euler buckling load. Add the cross-sectional area and the page also divides the load by the area to give a buckling stress; leave the area blank and that line says so.
The expression is Pcr = pi^2EI / (KL)^2, where K is the effective length factor. For a rectangular section the smaller of the two moments of inertia, the weak axis value, is used. The modulus of elasticity stays an input because it varies with material and grade and no default is confirmed in an authoritative source here. The expression itself follows from the derivation, while the explanatory material consulted is secondary and current as of October 2026.
Because the formula assumes elastic buckling, it cannot be used where the buckling stress approaches the yield strength of the material. Dividing the ranges by slenderness or a limiting slenderness is not covered. This is a reference aid and does not replace design work; review by a qualified engineer is required.
Frequently asked questions
The Euler expression assumes elastic behavior, so in that range the formula no longer applies. This page does not divide the ranges by slenderness or a limiting slenderness, so follow the procedure in the code you work to.
Buckling starts about the weaker axis, so the smaller of the two moments of inertia from the width and the depth is used. The result line states that the weak axis was taken.
The four values offered are the theoretical ones that follow from the Euler derivation. Design codes sometimes use adjusted factors, and in that case the value from the applicable code should be used.