Structural & Mechanical

Weld Throat & Capacity Calculator

Calculate fillet-weld throat, effective area, screening shear capacity and required weld length from a user-supplied design stress.

If I use a 6 mm fillet weld, how much shear can the weld carry under my chosen design basis?
High-consequence screeningUse this result to screen and frame the problem—not to approve regulated or high-consequence work.
Core formulae

Fillet weld screening reference

Theoretical throata = 0.707 z
Effective throat areaA = a × L_eff × n
Screening shear capacityV = τ_design × A
Simple arrangement sketch

Fillet weld on bracket plate

zVeffective weld length L_eff
1

Weld geometry and design basis

The entered design shear stress must come from your verified project design basis.

Results

Fillet-weld screening

Theoretical throat4.243 mm
Effective throat area1,697.1 mm²
Screening capacity305.5 kN
Applied utilisation32.7 %
Required effective length per line65.5 mm
Below the entered screening capacity

The result is only as valid as the design stress and effective length you entered.

Not an AS 4100 compliance result

This tool calculates geometry and capacity from a user-supplied design stress. It does not select the AS 4100 design stress, capacity factor, weld category, effective length rules or combined-load interaction for you.

Method

Fillet-weld throat = 0.707 × leg size. Capacity = entered design shear stress × total effective throat area.

Job-file record

Save the calculation, not just the number.

Copy a permalink that reloads these inputs, or download a PDF record with inputs, visible results, assumptions, a sensitivity note, date and disclaimer.

Important boundary

A calculator can show the arithmetic. It cannot establish every requirement that applies.

Confirm the actual equipment, loading, materials, condition, jurisdiction, contractual requirements, standard edition and current project documentation before using the result for design, repair, testing or lifting decisions.

Ask an engineer about this calculation →