Weld Strength Calculator
Construction & Home ImprovementEstimate the load capacity of a fillet or butt weld from its size, length, and allowable design stress.
Estimated Load Capacity
Estimated allowable load capacity, in pounds-force, at the entered design stress.
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Construction & Home Improvement calculators
Calculator Stats
Creators
Odeh Ahwal0people find this calculator helpful
Views
Helpful
Saved
Embeds
Construction & Home Improvement calculators
Frequently Asked Questions
What value should I enter for allowable stress?
Enter the allowable, safe design stress for your specific weld type and code, not the raw tensile strength of the electrode or base metal. For a fillet weld using a common E70 electrode under AWS D1.1, the allowable shear stress on the throat is 0.30 times the electrode's 70 ksi tensile strength, 21 ksi, the default used here. A butt weld typically follows a different allowable basis than a fillet weld, so use the correct value for your specific joint type and governing code.
Why is entering raw tensile strength instead of allowable stress dangerous?
Raw electrode or base metal tensile strength describes the weld's breaking point, not a safe working load. Using that number directly, without an appropriate safety factor, would significantly overstate what the weld can safely carry in service. This calculator is built around the allowable, already-reduced design stress specifically to avoid that mistake.
What is the 0.707 factor for a fillet weld?
A standard fillet weld has a roughly 45 degree triangular cross-section. The effective throat, the shortest distance through the weld metal that resists the load, is the leg size times the sine of 45 degrees, which equals 1 divided by the square root of 2, approximately 0.707.
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