Open the Fillet Weld Size & Strength Calculator
Calculate fillet weld throat and capacity from leg size, length, number of welds and electrode: AISC 360 ASD and LRFD, Eurocode 3 simplified method.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
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The Fillet Weld Size & Strength Calculator with sample data entered and the result showing.
What is the Fillet Weld Size & Strength Calculator?
A fillet weld fails along its throat — the shortest distance through the weld from the root to the face, equal to 0.707 times the leg size for an equal-leg weld. This calculator multiplies the throat by the effective length and the allowable shear stress to give the capacity of a weld group: choose the leg size, the length of each weld, how many lines of weld you have (for example both sides of a plate), the electrode strength (E60 to E110) and the base steel, and it returns capacities by three methods — AISC 360 allowable strength design (0.30·F_EXX), AISC 360 LRFD design strength (0.75 × 0.60·F_EXX) and the Eurocode 3 simplified method with the throat and the steel's ultimate strength and correlation factor.
It also reports the capacity per millimetre, the AISC minimum leg size for the thicker plate (Table J2.4) and the maximum leg size, optionally deducts start/stop craters, and shows utilisation and weld shear stress for a load you enter. For a 6 mm fillet weld 100 mm long on both sides in E70 the throat is 4.24 mm and the ASD capacity is 122.8 kN. These are quick design checks for loads through the weld centroid; eccentric loads, fatigue and the base-metal strength still need a full design check.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
AISC ASD, AISC LRFD and Eurocode 3 simplified method.
Minimum and maximum leg size per plate thickness.
Utilisation and shear stress for an applied force.
E60–E110 and S235–S460.
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Used for
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How it compares
A plain look at this tool next to the usual alternative.
| This engineering calculator | Desktop software | |
|---|---|---|
| Install | Nothing to install | Usually an app or program to install |
| Account | No signup | Depends on the product |
| Cost | Free to use | Free or paid, depends on the product |
| Where it runs | In your browser tab | On your computer |
Questions people ask
What is the throat of a fillet weld?
0.707 times the leg for an equal-leg 45° fillet.
ASD or LRFD?
They are alternative formats of the same AISC method; use the one your project requires.
Does it check the plate?
No — only the weld metal.
Is it free?
Yes.
How do I use the Fillet Weld Size & Strength Calculator?
1. Enter leg size, weld length and the number of lines. 2. Choose the electrode and base steel. 3. Read the capacities and the size warnings. 4. Enter your load to see utilisation.
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Capacity of fillet welds from leg size and length: AISC ASD/LRFD and Eurocode 3, with. Free to use.
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