Every maker who has cut into a fresh roll of cotton has been burned by shrinkage at least once. You cut your pattern, sew up a perfect t-shirt, wash it, and it comes out two sizes too small.
This post explains why fabric shrinks, what pre-shrunk really means, and how to plan for it.
Why fabric shrinks
Natural fibers like cotton, linen, and bamboo are stretched and stressed during spinning, weaving, and finishing. When they hit hot water and tumble dry, the fibers relax back to their natural relaxed state. That relaxation is what we call shrinkage.
Typical shrinkage rates for cotton knits range from 3 to 8 percent. So a 60 inch wide fabric can come out of the wash at 55 to 58 inches. Length shrinks too, sometimes more.
Pre-shrunk vs raw: the actual difference
Pre-shrunk fabric has been processed at the mill (washed, sanforized, or compactor-treated) to lock in most of the shrinkage before it gets to you. After pre-shrinking, a fabric might still shrink 1 to 2 percent more on home wash. But the big movement is already done.
Raw fabric has not been pre-shrunk. It will shrink the full 3 to 8 percent on first wash. Common with selvedge denim and some heritage cotton knits where makers actually want the raw character.
What to do as a maker
If your fabric is pre-shrunk
Wash and dry your fabric like you would the finished garment. Cut your pattern. Sew. Done. The fabric will shift very little on subsequent washes.
If your fabric is raw
Always pre-wash before cutting. Wash cold, tumble low or line dry. Iron flat. Let it sit overnight. Then cut your pattern. Skipping this step is how a custom-fit t-shirt becomes a crop top.
How to calculate yardage with shrinkage in mind
Add 10 percent to your yardage estimate when working with raw cotton. Order an extra half yard if the difference between two sizes is small. Better to have a bit left over than to be a quarter yard short.
How to read the product page
At KBM, our product pages call out pre-shrunk status explicitly. If a fabric is pre-shrunk, the description will say so. If it does not, treat it as raw and pre-wash before cutting.
If you are not sure, message us at support@kbmfabrics.com with the product link and we will give you a straight answer on shrinkage.
One last thing about color
First wash can also pull some loose dye out of cotton. This is normal and stops after the first wash. Wash dark colors with similar colors the first time. Most of our cotton fabrics are dyed with reactive or vat dyes which lock in well after that first cycle.
Want to test it yourself?
Order a swatch of any fabric, run it through your washer and dryer, and measure before and after. That is the only way to know for sure how a specific fabric will behave in your home setup.
For ongoing production runs, our wholesale program offers free priority swatches so you can test color and shrinkage across batches before committing.