How to Calculate Fabric Shrinkage

One of the development issues that we get asked about a lot is fabric shrinkage.

Here is some info about the subject.

When should I do a shrink test?
I would recommend to do a shrink test to every fabric that you are looking to use.

How to preform a shrink test?

  • Create a square pattern piece of 12.5" by 12.5"

  • Put the pattern piece on the fabric that you are testing and cut the square out of the fabric.

  • Using a permanent marker mark the warp (length of the fabric) with an arrow

  • Run the fabric through the your shrinkage process (re: washing, ironing, dying etc.).

  • Lay it flat on your cutting table (if you are testing washed denim do not steam or Iron the fabric after the wash cause it will effect the measurements).

  • Measure the fabric in both directions.

  • How to calculate the shrinkage percentage?

  • If the fabric shrunk, calculate the % of shrinkage using the following formula: every 1/8" of shrinkage is accounted as 1% shrinkage. For example, if the weft measured after the wash 12 1/8" that means a shrinkage of 3/8" in the weft = 3% shrinkage.

I tested the fabric and found out that it shrinks, how do I solve the issue for production?  
You can use one of these two solutions:

  • Building the Shrinkage % back into the pattern (your grader can do that digitally)

  • Pre-shrinking the fabric prior to cutting your production.

Which solution is right for me?
When the shrinkage % is in one direction only and measures up to 7-8%, you can built this % back into the pattern. 
However, if the % is more than 7-8% I would recommend the second option of preshrinking the fabric before cutting.
When the shrinkage is in both directions of the fabric, it will depend on the shrinkage % in each direction. If the shrinkage is not quite even between the 2 directions re: weft is 1% and warp is 10%, than it will depending on the actual style but you might need to preshrink the fabric (ask your grader for their recommendation). 

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