Often stretch sewing patterns will specify using a fabric with a certain amount of stretch factor. You will find that knits with different stretch factors will sew up differently and give a different look to your final product.
How to Determine Stretch Factor of fabric
To determine the amount of stretch, fold your fabric on the crosswise grain a few inches from the raw edge. Place a pin at least an inch from the edge and another 4 inches from the first pin.
See how far it stretches. You should not stretch the fabric to its absolute limit. Just enough that it has strong tension but is not overstretched.
If you love math, this is how you work out the percentage of stretch –
(amount fabric stretched /starting measurement ) x 100
So if your 4 inches stretches to 7 inches, it stretched by 3 inches.
Our formula is ¾ x 100 = 75% stretch factor.
Don’t worry if you are not great at math. I have a printable chart you can use.
Click on the link above and a PDF file will come up for you to print. Make sure your printer’s scaling is set to “none” or “100%” and check the test square to ensure it has printed the correct size.
For most stretch items like dresses and tops, it is the crosswise measurement that is important as this is the amount of stretch going around your body.
For items such as leotard sewing patterns and swimwear, you will also need to measure the lengthwise grain stretch. Some lycra swim and dance fabrics have a lengthwise stretch which is greater than the crosswise stretch and this can affect how you place your pattern pieces when cutting.
A good knit fabric should recover to its starting point after being stretched. This is called recovery. If your fabric doesn’t recover to its original position, you will find that after a short wear, your garment will look baggy and start to stretch out of shape.
So that’s how you work out the stretch factor of your fabric!
Now you know how to work out your fabric's factor here are a few of the lovely things you can make.