Weld Throat Thickness Estimator
Calculate the effective throat thickness of a weld. This is the most critical dimension for calculating the strength of a weld joint.
Weld Dimensions
Enter the size of your weld to calculate its effective throat.
The True Measure of Strength: Throat Thickness
When calculating the strength of a weld, the most important dimension is not its leg size or its face width, but its **effective throat thickness**. This represents the shortest distance from the root of the weld to its face. It is the plane through which a weld will fail in shear, and therefore, it is the dimension used in all engineering strength calculations.
Fillet Welds vs. Butt Welds
- Fillet Welds: For a standard, convex fillet weld with equal legs, the throat is calculated as `0.707 × Leg Size`. The number 0.707 is the sine of 45°, which represents the shortest distance in a 45-degree right triangle.
- Butt Welds: For a "Complete Joint Penetration" (CJP) butt weld, the weld metal fully fuses through the entire thickness of the base material. In this case, the throat thickness is simply equal to the thickness of the base material being welded.