Fillet Weld Strength Calculator

Calculate allowable load and shear strength per AWS D1.1 and AISC standards.

Design Code

Unit System

Leg Size (mm)

Weld Length (mm)

Electrode Classification

Load Direction

Transverse loading provides higher strength per AWS D1.1

Number of Weld Lines

Base Metal Yield Strength (MPa)

For checking base metal capacity (A36 = 250 MPa / 36 ksi)

Common Filler Metals

AWS Class	FEXX (ksi)	FEXX (MPa)
E6010, E6011	60	415
E7018, ER70S-6	70	480
E8018	80	550
E9018	90	620
E10018	100	690

Fillet Weld Strength Theory

AWS D1.1 / AISC Formula

Allowable Load = Allowable Stress x Effective Throat x Length x Directional Factor

Effective Throat (a) = Leg Size x 0.707 (for equal leg fillets at 45 degrees)

Allowable Stress (ASD Method)

AWS D1.1: Fv = 0.30 x FEXX (shear on effective area)
AISC: Fv = 0.30 x FEXX (same basis)
Example: E70XX: Fv = 0.30 x 70 = 21 ksi allowable

Directional Strength Increase (AWS D1.1)

Longitudinal: Factor = 1.0 (base case)
Transverse: Factor = 1.5 (50% increase per AWS)
Angle theta: Factor = 1.0 + 0.5 x sin^1.5(theta)

Minimum Fillet Weld Sizes (AWS D1.1)

Base metal up to 6mm (1/4"): 3mm (1/8") min
Base metal 6-13mm (1/4"-1/2"): 5mm (3/16") min
Base metal 13-19mm (1/2"-3/4"): 6mm (1/4") min
Base metal over 19mm (3/4"): 8mm (5/16") min