T-shirt pattern quest pt. 2 : Calculating the amount stretch in a knit fabric

Patterns for styles made out of a knit fabric need to include the amount of wearing ease for the desired fit. In some cases the wearing ease is actually negative ease. Negative ease means the pattern measurement is smaller than the actual corresponding body measurement. A good example of this would be yoga pants in which the pants stretch to fit a particular size. In some cases the pattern has positive wearing ease because the style is larger than the corresponding body measurements, such as an oversized sweatshirt. Determining how much to reduce a pattern for a desired type of fit requires first determining a knit fabrics stretch factor.

Note - My pattern is intended for knits that have already been pre-washed and shrunk from retail store knits. So no extra allowance is included for shrinkage.

At this point I needed to check the amount of stretch in this fabric. Fold the fabric so that you are not testing on the edge of the fabric. Place two pins 5 inches apart.

Pick up the fabric and hold the left pin in your left hand at the zero mark and then stretch the fabric as far as it will go with your right hand. Watch where the right pin stretches on the stretch ruler. In this case, my fabric stretches about 30%. Only stretch the fabric as far as it will reasonably go without overly stressing the fabric.

Let go of the fabric with your right hand and watch to see if the fabric returns to it's original position. Knits that do not return at all, have no recovery. In this case, my fabric returned to the 10% mark, which isn't great, but probably ok for a top.

I had forgotten, but this particular fabric is an interlock rather than a jersey. Interlocks do not stretch nearly as much as a jersey. I had originally planned on adding about 1 inch of extra wearing ease because I wanted a bit looser fit. Now I wonder if I should add a bit of extra? Once I work that out, I will modify my pattern and cut it out.