Fillet Weld Calculator
Checks a fillet weld's design resistance using the simplified method of Eurocode 3, and (optionally) an applied-load utilisation check.
Standards used on this page:
- BS EN 1993-1-8:2005+A1:2014 (Eurocode 3, Part 1-8) — Section 4.5.3.3, simplified method for fillet welds; Table 4.1, correlation factor
- UK National Annex to BS EN 1993-1-8 — partial factor γM2 = 1.25
- BS EN 10025-2 — nominal ultimate tensile strength (fu) of connected steel grades
Accuracy & scope note:
- Simplified method only — treats the resultant applied force as pure longitudinal shear on the weld throat. This is always safe, but is conservative for welds loaded transversely or at an angle, where the fuller "directional method" would allow a higher resistance. That method is not implemented here.
- Fillet welds only — butt welds are not covered.
- Checks the weld itself only — does not check the parent material either side of it (e.g. plate shear or block tearing along the weld line).
- Assumes throat thickness a = 0.7 × leg length for an equal-leg fillet weld, unless you enter the throat thickness directly.
This tool provides preliminary, indicative structural calculations only, intended to assist with initial sizing and understanding. It is not a substitute for assessment by a qualified structural engineer, and cad-steel.co.uk accepts no responsibility for its use in any final design. Always have connection designs checked and approved by a competent engineer before construction.