What is effective throat in fillet weld?

a = 0.707 × leg length (s) for 45° fillet.

Typical allowable shear stress for weld?

0.3–0.4 × electrode tensile strength (e.g., 140–170 MPa for E70XX).

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Weld Design Calculator

Design fillet and butt welded joints: calculate throat size, leg length, weld strength, allowable load. Lap, T-joint, butt joints with parallel/perpendicular loading.

Required Throat

7.1 mm

Fillet weld, 200 kN load, τ=140 MPa

Welded Joint Strength

Featured: Fillet Weld Throat, Butt Weld, Load Direction

Applied Load P (kN)

Weld Type

Weld Length L (mm)

Plate Thickness t (mm)

Allowable Shear Stress τ (MPa)

Allowable Tensile Stress σ (MPa)

Weld Strength vs Throat Size

Capacity for different throat thicknesses

Fillet Weld Strength

P = τ × 0.707 s × L (parallel)
P = 1.414 τ × 0.707 s × L (perpendicular)

Butt Weld

P = σ × t × L

Enter parameters to see results

Weld Design Guidelines

Fillet Weld

Leg length s: ≈ plate thickness

Throat a: 0.707 × s

Perpendicular load: 1.414× stronger

Typical Stress

E60XX: τ ≈ 120 MPa

E70XX: τ ≈ 140 MPa

E100XX: τ ≈ 200 MPa

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