By Zencalcy Editorial TeamLast reviewed About us
A fillet weld is sized by its leg, but it carries load on its throat: 0.707 × leg for a 45° fillet. Capacity is throat × length × allowable stress. Filler metal consumption follows the deposited volume and a deposition efficiency, which is where the electrode count comes from.
Weld throat, capacity and electrode consumption.
throat = 0.707 × leg capacity = throat × length × allowable stress filler = throat × leg × length × density
Allowable shear on a fillet weld is commonly 0.3 × electrode tensile strength for a 2:1 safety factor: E70 gives about 21 ksi. Deposition efficiency is 60–70% for stick, 90% for MIG. Weld volume is approximately 0.5 × leg² × length.
| Symbol | Meaning |
|---|---|
| leg | Fillet weld leg size. |
| throat | Effective throat, 0.707 × leg. |
| L | Weld length. |
Throat 0.177 in, capacity 37,100 lb in shear, and about 0.12 lb of filler metal per pass.
Continue with the Beam Deflection Calculator, Beam Load Calculator, Bending Stress Calculator, or the Wood Beam Span Calculator — or browse more structural & workshop and all construction calculators.
The shortest distance from the root to the face, 0.707 × leg for an equal-leg 45° fillet.
Results use standard construction estimating arithmetic: volumes from measured area and depth, unit weights from published material densities, and code-referenced spans or clearances where the page names a code. Quantities are rounded up to whole saleable units and include the stated waste allowance. These tools are planning aids, not structural design, and do not replace a licensed engineer, a local code check, or a contractor's site measurement.
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Content updated: September 2026