Fillet Weld Size & Strength

Effective throat from the leg size, and the shear capacity of a fillet weld from its leg, length and allowable shear stress. A quick sizing check, not a code-compliant connection design.

Weld

Leg size (s) mm

Total weld length mm

Sum of all effective weld length carrying the load.

Allowable shear stress MPa

Depends on electrode & code. E.g. ~144 MPa for E70 at typical allowable; use your code's value.

Results

Shear capacity—

Effective throat (a = 0.707 s)—

Effective weld area—

Capacity per mm of weld—

Throat a = 0.707 × leg (equal-leg fillet). Capacity = a × length × allowable shear. This treats the weld in simple shear; real joints may also see bending, eccentricity or combined stress — size with margin and follow your governing code (AWS, Eurocode, etc.).