Estimate longitudinal weld shrinkage with steel reference allowances or a custom measured ratio, in inches, mm, cm, feet or meters.

Longitudinal shrinkage estimate only. Steel reference allowances are rough assembly guides; verify against comparable weld trials. Transverse and angular distortion are different.

Weld Shrinkage Formula

The following formula estimates longitudinal shrinkage from a dimensionless ratio. TWI gives rough steel assembly allowances of 0.8 mm per 3 m for fillet welds and 3 mm per 3 m for butt welds. These are approximate guides, not predictions for every procedure. The prior numeric factors remain available as legacy ratios without their unsupported weld-type recommendations. Transverse shrinkage and angular distortion require different models.

TS = WL × SF

Variables:

  • TS is the total shrinkage (same length units as WL, e.g., inches or mm)
  • WL is the weld length (e.g., inches or mm)
  • SF is the shrinkage factor (dimensionless ratio, e.g., in/in or mm/mm)

To calculate the total weld shrinkage, multiply the weld length by the shrinkage factor.

What is Weld Shrinkage?

Weld shrinkage is the reduction in size that occurs in the metal as it cools after welding. The heat from the welding process causes the metal to expand, and as it cools, it contracts, leading to shrinkage. This can affect the overall dimensions of the welded structure and must be accounted for in the design and fabrication process to ensure the final product meets the required specifications.

How to Calculate Weld Shrinkage?

The following steps outline how to calculate the total weld shrinkage.

  1. First, determine the weld length (WL).
  2. Next, choose the stated steel longitudinal reference or determine a custom shrinkage factor (SF) from comparable weld trials, as a dimensionless ratio (e.g., in/in or mm/mm).
  3. Next, gather the formula from above = TS = WL * SF.
  4. Finally, calculate the total shrinkage (TS) in the same length units as WL.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

weld length (WL) = 50 inches

shrinkage factor (SF) = 0.001 in/in

total shrinkage (TS) = WL × SF = 50 × 0.001 = 0.05 inches