Weld Strength Calculator — Formula
## Fillet Weld Strength
Fillet welds fail through the throat, which is the shortest path through the weld cross-section.
### Key Relationships
**Effective throat = 0.707 x leg size** (for equal-leg fillets at 45 degrees)
**Capacity = throat x length x allowable shear stress**
The 0.707 factor is cos(45 degrees) = sin(45 degrees), representing the minimum cross-section through the triangular fillet.
Fillet welds fail through the throat, which is the shortest path through the weld cross-section.
### Key Relationships
**Effective throat = 0.707 x leg size** (for equal-leg fillets at 45 degrees)
**Capacity = throat x length x allowable shear stress**
The 0.707 factor is cos(45 degrees) = sin(45 degrees), representing the minimum cross-section through the triangular fillet.
Exemplo Resolvido
A 6 mm fillet weld, 200 mm long, with 124 MPa allowable shear (E70 electrode).
- Throat = 0.707 x 6 = 4.24 mm
- Capacity = 4.24 x 200 x 124 = 105,152 N = 105.2 kN
- Strength per mm = 4.24 x 124 / 1000 = 0.526 kN/mm