Fillet Weld Size Calculator
Leg size needed for a load — and the min/max size rules checked.
Minimum fillet sizes exist for HEAT, not strength — a tiny weld on thick plate quenches too fast and cracks. Doubling length beats doubling leg: capacity is linear in both, but volume (cost) grows with s².
Formula
Fillet Weld Size Calculator is a free fillet weld size for welding engineers, fabricators and CWI inspectors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Fillet Weld Size Calculator
Leg size needed for a load — and the min/max size rules checked. The calculation implements s = P·√3·γ/(0.707·L·f_u); min size per IS 800 Table 21 (IS 800 Table 21; AWS D1.1 Table 5.7). Minimum fillet sizes exist for HEAT, not strength — a tiny weld on thick plate quenches too fast and cracks. Doubling length beats doubling leg: capacity is linear in both, but volume (cost) grows with s².
How to use Fillet Weld Size Calculator
- 1Enter Load on joint in kN.
- 2Enter Available weld length in mm.
- 3Enter Electrode f_u in MPa.
- 4Enter Thicker plate thickness in mm.
- 5Read Required leg size, Code minimum (by plate t) instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Fillet Weld Size Calculator?
- ✓Implements the standard formula — s = P·√3·γ/(0.707·L·f_u); min size per IS 800 Table 21
- ✓Reference cited on-page: IS 800 Table 21; AWS D1.1 Table 5.7
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Built-in engineering verdict flags out-of-range results instantly
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Fillet Weld Size Calculator use?+
It computes s = P·√3·γ/(0.707·L·f_u); min size per IS 800 Table 21, per IS 800 Table 21; AWS D1.1 Table 5.7. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Minimum fillet sizes exist for HEAT, not strength — a tiny weld on thick plate quenches too fast and cracks. Doubling length beats doubling leg: capacity is linear in both, but volume (cost) grows with s².
Does this follow AWS/IS welding codes?+
Each tool implements the formula from the cited code or handbook (AWS D1.1, IS 800, ISO/EN). Qualified WPS values always govern over any calculator for code work.
Is the Fillet Weld Size Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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