Use the calculator to determine the required fillet weld leg size (weld size), required weld length, or weld capacity based on applied load, weld length/size, number of weld lines, and allowable weld shear stress.
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Fillet Weld Effective Throat Formula
The following formula is used to calculate the theoretical (effective) throat thickness of an equal-leg 45° fillet weld from the weld leg size (weld size).
t = 0.707 * w
Variables:
- t is the effective throat thickness
- w is the fillet weld size (leg size / leg length)
To calculate the effective throat thickness, multiply the fillet weld leg size by 0.707 (≈ sin 45°).
What is a Fillet Weld?
A fillet weld is a type of weld that joins two pieces of metal at a right angle or an oblique angle. It is commonly used in various welding applications due to its simplicity and strength. The fillet weld is characterized by its triangular cross-section and is typically used to join two surfaces that are perpendicular or at an angle to each other. This type of weld is often used in structural steelwork, shipbuilding, and other applications where strong, reliable joints are required.
How to Calculate Fillet Weld Throat Thickness?
The following steps outline how to calculate the effective throat thickness of an equal-leg fillet weld.
- First, determine the fillet weld leg size (w) (also called the fillet weld size).
- Next, calculate the effective throat thickness using the formula t = 0.707 × w (for a 45° equal-leg fillet weld).
- Finally, use the calculator above if you need required weld size, required weld length, or weld capacity for a given load.
Example Problem :
Use the following variables as an example problem to test your knowledge.
Fillet Weld Leg Size (w) = 10 mm
Effective Throat Thickness (t) = 7.07 mm