Work out weld strength instantly with clear inputs, formula shown and shareable results.
Fillet weld capacity is the effective throat area multiplied by the allowable shear stress, conventionally 0.30 times the electrode tensile strength. Throat area is 0.707 times leg size times effective length, so capacity is directly proportional to leg size, not to its square.
Throat area
A = 0.707 x leg x effective length
Capacity
Capacity = A x 0.30 x electrode tensile strength
Preliminary estimate only. Weld capacity must be verified against the governing structural welding code, including electrode matching and inspection requirements.
A = 0.707 x leg x effective length. Fillet weld capacity is the effective throat area multiplied by the allowable shear stress, conventionally 0.30 times the electrode tensile strength.
Some codes allow a higher stress for welds loaded transversely than longitudinally. The 0.30 factor used here is the conservative direction-independent value.
This calculator takes 3 inputs: Fillet leg size, Effective weld length, Electrode tensile strength. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.