SettingsSettings for this calculationUS
The nominal leg size of the equal-leg fillet weld.
The leg, not the throat — a fillet weld's leg is the distance up the fusion face, and the throat that carries the load is about 0.707 of it for an equal-leg weld. The calculation makes that conversion. A leg larger than the thinner plate it joins cannot be deposited properly, and most codes also set a minimum leg for the thicker part being welded, so the size is bounded at both ends rather than chosen freely.
The electrode classification, which sets the weld metal's classification strength FEXX.
The electrode the welder will actually use, because its classification sets the strength the weld metal is designed to. Matching the electrode to the base metal is the usual rule; an over-matched electrode does not make the joint stronger once the base metal governs, and an under-matched one silently lowers the capacity this calculation reports.
The total effective length of the weld seam.
The EFFECTIVE length — the length that is actually fused — which on a short weld is less than the length you measure, because the start and the stop are not full size. Where a weld wraps a corner or returns along an edge, count the return only if it is genuinely made. Intermittent welds are the sum of the runs and not the length of the joint they are spread over.
Nominal weld shear capacity
71.4 kips
This is the NOMINAL weld strength Rn from AISC 360 §J2.4. It is not a usable design capacity: apply φ = 0.75 for LRFD, or divide by Ω = 2.00 for ASD, and check the connected base metal separately — the base metal, not the weld, governs many joints.
- Effective throat thickness
- 0.22 in
- Capacity per unit length of weld
- 9.21 kips/in
They open the calculator with your figures already in it
Fillet Weld Shear Capacity Calculator: 71.39 kips — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Show calculation logicHide calculation logic
How this was calculated
Formula source(s)
- AISC 360 §J2.4 (Table J2.5): nominal weld strength Rn = 0.60×FEXX×Awe, where the effective throat Awe uses te = 0.707×leg size for an equal-leg fillet weld — consistent with AWS D1.1 Table 2.3
Inputs used
- Fillet Weld Leg Size
- 0.31 in
- Electrode
- E70XX (FEXX = 483 MPa / 70 ksi)
- Total Weld Length
- 7.75 in
Intermediate steps
- Effective throat thickness
- 0.22 in
- Capacity per unit length of weld
- 9.21 kips/in
Confidence note: This is the NOMINAL weld strength Rn from AISC 360 §J2.4. It is not a usable design capacity: apply φ = 0.75 for LRFD, or divide by Ω = 2.00 for ASD, and check the connected base metal separately — the base metal, not the weld, governs many joints.
What this calculation does not cover
- 0.60 FEXX is the base case, for a weld loaded parallel to its own axis. AISC J2.4 permits a directional increase for welds loaded at an angle to their length — up to 1.5 times for a fillet loaded transverse to it — so this reads conservative for an end weld and exact for a side weld, and a group containing both has to be handled by the code's combination rule rather than by adding the two lengths together.
- Length is taken as fully effective however long it runs. For end-loaded fillet welds longer than about 100 times the leg size AISC applies a reduction factor, because stress along a long lap is not uniform and the far end does less work than the near end; below four times the leg size the effective length is cut back instead. A long lap weld does not deliver capacity in proportion to its length.
- The leg size is accepted without any of the rules that bound it. AISC Table J2.4 sets a minimum leg by the thickness of the thicker part joined, so the weld cools slowly enough not to crack, and a weld run along a plate edge is capped at the plate thickness — less 1/16 in (1.6 mm) on material 1/4 in (6 mm) and over — so the edge is not melted away. A capacity computed from a leg outside those bounds describes a weld that will not be accepted.
- The result is a group total, and it assumes the load passes through the group's centroid. Where it does not — a bracket, a shear tab, a bracing gusset — the weld carries torsion on top of direct shear, the far corner reaches its limit while the rest is barely stressed, and the capacity from an instantaneous-centre analysis falls well below this length × strength product.
Add the equipment this sizes
This result is a specification — 71.4 kips — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-06 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- AISC 360 §J2.4 (Table J2.5): nominal weld strength Rn = 0.60×FEXX×Awe, where the effective throat Awe uses te = 0.707×leg size for an equal-leg fillet weld — consistent with AWS D1.1 Table 2.3
Which documents these citations point at
Standards referenced: AISC 360 (American Institute of Steel Construction, United States).
Cite this page
Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.