Check a simple linear fillet weld's allowable capacity, or analyze an eccentrically-loaded weld group by the AISC elastic (weld-treated-as-a-line) method.
ASD allowable = 0.30 × FEXX, per AISC 360 Table J2.5.
Coordinates are in inches, in any consistent local system; the tool computes the centroid for you.
The load point is where the applied force actually acts (e.g. at a bracket's bolt line); it doesn't need to line up with the weld group.
A fillet weld fails in shear through its throat, the shortest distance from root to face. Capacity is the throat area times the allowable shear stress.
Rule of thumb: with E70, every 1/16 in of leg carries 0.928 kip/in.
When the load doesn't pass through the weld group's centroid, such as a bracket on a column flange, the welds carry direct shear plus a twisting moment. The elastic method adds the two as vectors at each segment end and corner:
f = √[(Fx/L − M·y/J)² + (Fy/L + M·x/J)²]
For example, two 8 in vertical welds 6 in apart, with a 20 kip load 8 in from the centroid: J = 229.3 in³, M = 160 kip·in, and the critical corner sees 4.35 kip/in. That needs a 0.293 in leg, so a 5/16 in fillet works at 94% of capacity.
The elastic method is conservative. AISC's instantaneous center (IC) method accounts for weld ductility and for transversely loaded fillets being up to 50% stronger. The AISC Manual's eccentric weld tables use it, and it usually allows a smaller weld. This calculator uses the elastic method only.
Base metal shear rupture, minimum and maximum fillet sizes, LRFD, and fatigue.
The IC method, base metal checks, bolted-plus-welded combinations, and full connection design packages are exactly the kind of structural work Jeffrium takes on.