Weld Throat Calculator

Inputs

Design basis

Use ASD with service loads or LRFD with factored loads.

Leg A (z1)

First fillet leg size measured from the root.

Leg B (z2)

Second fillet leg size measured from the root. Set equal to Leg A for a standard equal-leg fillet.

Effective weld length (L)

Length of sound weld carrying the load.

Root-opening allowance (g)

Conservative reduction for root opening or fit-up gap if the weld size is not increased to compensate.

Electrode

Filler-metal classification sets F_EXX.

Applied load (P)

Load to compare with weld capacity. Use service load for ASD or factored load for LRFD.

Default result

Effective throat(a_eff)

4.243mm

Theoretical throat minus root-opening allowance.

Also computed

Theoretical throat(a)4.243mm

Weld capacity(R)61,480N

61.48 kN · 6.27 t

Utilization(U)0.8133

Within weld-metal capacity.

Applied load / weld capacity.

Required equal leg(z_req)4.88mm

Equal-leg size for the entered load and root allowance.

Required throat(a_req)3.451mm

Capacity per length(R/L)614.8N/mm

Method notes 4 notes

For a right-angle unequal-leg fillet, theoretical throat is z1*z2 / sqrt(z1^2 + z2^2). Equal legs reduce to 0.707*z.
Effective throat is reduced by the entered root-opening allowance. If the weld size is increased or testing demonstrates the required throat, set the allowance to zero.
ASD basis uses 0.30*F_EXX and should be compared with service loads.
This checks weld metal only. Base metal, minimum/maximum weld size, end returns, intermittent welds, fatigue, eccentric weld-group behavior and code-specific detailing are outside this simple throat check.