Weld Strength Calculator

May 7, 2025

Weld Strength Calculator

Our weld strength calculator will provide insight into how you can expect materials to perform based on the welds you intend to make.

Disclaimer: Although the calculations are accurate and conservative, this will in no way substitute for proper engineering and analysis and should only be used as a general guide. We assume no responsibility for the data presented, or how you choose to use it.

Weld Strength Calculator

Butt Weld vs Fillet Weld

You’ll need to choose a specific type of weld to make the calculation. Choose Butt Weld if you are basically taking two flat pieces and joining them along an edge, or Fillet Weld if one piece is perpendicular to the other.

ASD vs LRFD

In the calculations, the reason we’re displaying two different methods (Allowable Stress Design – ASD and Load and Resistance Factor Design – LRFD) is that it’s important to design products to be safe, but also to know what their theoretical maximums are. So we’re trying to understand what the safe, and accurate, limits of our welds are. These descriptions are complete oversimplifications, but here goes:

  • ASD (“Safe Guess”): ASD calculations, make a “safe guess”. For example using ASD method, results on this calculator tell us a safe shear stress level on that weld. This can be generally used by a consumer of the output to assess how much their weld will carry safely with that designed material and method.
  • LRFD (“Precise Guess”): LRFD provides more “precise guessing”. For LRFD the calculation includes all sorts of variations based on the application materials. The outputs using LRFD calculation say “your material, with all known variation, is predicted to handle X load at this percentage before the material bends too much, stretches past any acceptable limits, or otherwise fail completely

Example

Using the calculator we might see that for A36 steel, if we make a .25″ weld that is 1″ long, we should be able to bank on it safely taking 1691.50 lbs (7523.79 N) of stress without failing. It will most likely actually take at least 4613.18 lbs (20519.42 N) to tear or break the weld.

But again these are estimations and they make assumptions:

  • Your weld is perfect. All the prep was done properly, there are no inclusions, you had plenty of penetration, your settings were correct, etc.
  • The material was perfect. There were no weak spots or defects in the material.

So, always consider the safety factor depending on the importance of the weld in the application.

John P.
John P.

Founder and Chief Mad Scientist of Texas Metal Works.
Author, fabricator, philosopher, cook, artist, photographer.

Articles: 4

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