What is a fillet weld leg size?

The leg size (w) is the length of each leg of the triangular fillet weld cross-section. It is measured along each base metal face joined by the weld.

What is the effective throat of a fillet weld?

The effective throat (t) is the perpendicular distance from the root of the fillet weld to the theoretical weld face. For a standard 45° fillet, throat = leg × 0.707.

What electrode strength does this calculator assume?

The calculator uses E70XX electrodes (70 ksi nominal tensile strength), the most common classification for structural steel welding per AWS D1.1.

What is the difference between shear and transverse loading?

Shear (parallel) loads act along the weld axis. Transverse (perpendicular) loads act across the weld. Fillet welds carry about 50% more load under transverse loading for the same weld size.

Does this follow LRFD or ASD?

The calculator provides both LRFD (φ = 0.75) and ASD (Ω = 2.00) results so you can use whichever design method your project requires.

What is the minimum weld size per AWS D1.1?

AWS D1.1 Table 6.1 sets minimums based on thicker base metal thickness: 3/16" for up to 1/4", 1/4" for 1/4"–1/2", 5/16" for 1/2"–3/4", and 3/8" for metal over 3/4".

Weld Size Calculator

Name: Weld Size Calculator
Availability: InStock
Author: Nham Vu

Calculate minimum fillet weld leg size and effective throat from applied load, weld length, and base metal yield strength.

Weld Parameters

Applied Load

Total Weld Length

Thicker Base Metal Thickness (for AWS minimum check)

Base Metal Yield Strength (Fy)

Load Direction

Shear (parallel) Transverse (perpendicular)

Enter load, weld length, and material — then click Calculate.

Required Leg (w)

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Effective Throat (t)

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AWS D1.1 Minimum Weld Size

Unit Shear Stress on Weld

Applied

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Capacity (LRFD, φ=0.75)

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Design Capacity Summary

Method	Capacity	DCR

Standard Weld Sizes to Specify

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Summary

Calculate minimum fillet weld leg size and effective throat from applied load, weld length, and base metal yield strength.

How it works

Enter the applied load (force) the weld must carry.
Enter the total weld length available.
Select the base metal yield strength (steel grade).
Choose the load direction: shear (parallel) or tension/compression (transverse).
The calculator returns required weld leg size, effective throat, and weld strength.

Use cases

Size fillet welds for structural steel connections.
Verify weld adequacy for bracket and gusset plate designs.
Determine minimum weld size for base plate attachments.
Check AWS D1.1 compliance for shop and field welds.
Estimate weld requirements for machinery frames and supports.
Compare shear vs. transverse load capacity for the same weld.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu