Fillet Weld Area / Throat Geometry
Estimates a fillet weld's theoretical cross-section area (and, for equal-leg geometry, the leg/throat relationship) from idealized triangular geometry — a geometric estimate only. It does not measure a real weld, does not verify structural design, does not decide inspection or standard-compliance acceptance, and does not approve a WPS/PQR.
Engineering calculator — results require technical review before production use.
Source & assumptions
No fillet-weld geometry formula stated by ISO 5817, ISO 9606, ISO 15614, AWS, IWE Module 2, or any other source is cited or claimed for this calculator. Its core arithmetic (theoretical triangular area and, for equal-leg geometry, the leg/throat relationship) is this project's own applied plane geometry — the standard area and altitude relationships of a right triangle — not attributed to any welding standard or compendium. See W020_FILLET_WELD_AREA_SPEC.md Section 3 for the full derivation.
Assumptions
- Idealized triangular fillet geometry — the cross-section is modeled as a triangle formed by two legs and a theoretical face, with no allowance for real weld profile.
- Equal-leg modes (equalLegFromLegLength, equalLegFromThroat) assume a 90° angle between the two members, giving a 45° theoretical face and equal legs.
- The unequal-leg mode (unequalLegFromLegs) assumes a 90° angle between the two members; it does not assume the legs are equal.
- Dimensions are entered in mm; area is calculated in mm².
- No overfill, convexity, or concavity allowance.
- No penetration or root-gap allowance.
- No design-code acceptance check of any kind.
- For the unequal-leg mode, no throat size is calculated — no single throat convention has been confirmed for that geometry (see W020_FILLET_WELD_AREA_SPEC.md Section 3, Model C).
- Result requires engineering review — this calculator does not determine whether a fillet weld's actual or theoretical size is adequate for any application.
Limitations
- Theoretical geometry estimate only.
- Not a measured weld size.
- Not weld inspection acceptance.
- Not an ISO 5817 / ISO 9606 / ISO 15614 / AWS compliance decision.
- Not structural design verification.
- Not a throat-size acceptance decision.
- Does not approve a WPS or PQR.
- Not production acceptance.
- Does not account for actual weld profile, penetration, root gap, fit-up tolerance, undercut, convexity, concavity, grinding, repair welding, or measurement uncertainty.
- Does not replace welding coordination review, design review, inspection, macro examination, procedure qualification, or engineering judgement.