Most fabric should be washed before you cut and sew it, because cotton, linen, and many blends shrink when they first meet water and heat
If you wash a finished garment and it shrinks, you cannot undo that. If you wash fabric before sewing and it shrinks, you can account for the loss and adjust your pattern. That is the core reason: pre-washing protects the fit of what you make.
How much shrinkage happens depends on the fiber. Cotton and linen shrink noticeably—often 2 to 5 percent in the first wash. Polyester and acrylic shrink very little or not at all. Blends fall somewhere in between. If you are making a fitted garment like a dress or trousers, even 2 percent shrinkage changes how it sits on your body.
The second reason to pre-wash is that some dyes, especially on dark fabrics, bleed into the water. Washing before sewing means loose dye comes out now, not onto a light-colored seam allowance or interfacing later.
Key Takeaways
- Cotton, linen, and cotton-blend fabrics shrink 2 to 5 percent in the first hot or warm wash, so pre-washing prevents your finished garment from becoming too small.
- Dark fabrics often release loose dye in the first wash, and this dye can stain seam allowances and interfacing if you do not wash before sewing.
- Synthetic fabrics like polyester and acrylic shrink very little, so pre-washing matters less for them, though it still removes loose dye.
- Wash fabric in the same temperature and cycle you will use for the finished garment, because different water temperatures cause different amounts of shrinkage.
- Dry fabric on low heat or lay it flat to dry, then press it flat before measuring and cutting, so wrinkles do not throw off your pattern.
Which fabrics actually need pre-washing
Natural fibers—cotton, linen, wool, silk—almost always shrink. If your pattern calls for cotton or linen, assume you need to pre-wash. The exception is fabric labeled "pre-shrunk" or "sanforized," which means the mill has already heat-treated it to lock in the size. Even then, a small amount of shrinkage can still happen, so if you are making something fitted, pre-washing is still the safer choice.
Blends that are mostly cotton or linen (like 65 percent cotton, 35 percent polyester) shrink enough to matter. Pure polyester, acrylic, and nylon shrink so little that pre-washing is optional—though you may still want to wash dark synthetics to remove loose dye.
Wool is its own category. Wool can shrink dramatically and felt if you use hot water or a regular washing machine cycle. If you are working with wool, hand-wash it in cool water with wool-specific detergent, or use your machine's wool cycle if it has one.
How to pre-wash without damaging the fabric
Wash fabric in the same temperature water you will use for the finished garment. If you plan to wash the garment in cold water, wash the fabric in cold water. If you will use warm water, use warm water now. This matters because hot water causes more shrinkage than cold water, so if you pre-wash in hot water and then wash the garment in cold, the garment will still shrink a little more.
Use a gentle or delicate cycle if the fabric is loosely woven, lightweight, or has a nap or pile (like velvet or corduroy). For sturdy cotton and linen, a regular cycle is fine. Do not use bleach unless you plan to bleach the finished garment.
Dry the fabric on low heat in the dryer, or lay it flat or hang it to air-dry. High heat causes extra shrinkage and can damage some fibers. Once it is dry, press it flat with an iron on the appropriate heat setting so wrinkles do not throw off your measurements when you lay out the pattern.
When you can skip pre-washing
If the pattern is loose-fitting—a t-shirt, a straightforward shift dress, or wide trousers—small shrinkage may not matter enough to worry about. You have built-in room for the fabric to move. Still, if the fabric is dark, washing it first removes dye that could stain lighter thread or interfacing.
Fabric labeled "pre-shrunk" has already been treated at the mill, so shrinkage risk is very low. You can usually skip pre-washing, though reading the bolt end or care label will tell you for certain.
Specialty fabrics like silk charmeuse, delicate laces, or fabrics with special finishes (like water-resistant coating) sometimes should not be pre-washed because washing can damage the finish or change the hand of the fabric. Check the bolt end or ask the fabric seller before you wash.
What happens if you do not pre-wash
The most common outcome is that your finished garment shrinks after the first wash, and it no longer fits the way you intended. A dress becomes shorter and tighter. Trousers ride higher at the ankle. A fitted shirt pulls across the chest.
The second risk is dye bleeding. Dark fabrics release loose dye in the first wash, and if that dye contacts light-colored seam allowances, thread, or interfacing, it can leave permanent stains. These stains are visible from the inside and can show through to the outside on light fabrics.
Neither of these problems is catastrophic if the garment is loose-fitting or if you do not mind a slightly smaller finished size. But for fitted garments, the difference between pre-washing and not pre-washing is often the difference between a garment that fits and one that does not.
Pre-washing for different fabric types
| Fabric Type | Shrinkage Risk | How to Pre-Wash |
|---|---|---|
| Cotton, linen, cotton blends | High (2–5%) | Warm or cold water, gentle or regular cycle, low heat dry |
| Wool | Very high (can felt) | Cool water, wool cycle or hand-wash, lay flat to dry |
| Silk, delicate fabrics | Varies; check label | Hand-wash cool water or skip if label says dry-clean only |
| Polyester, acrylic, nylon | Low | Optional; wash if dark to remove loose dye |
| Pre-shrunk cotton | Very low | Optional; still recommended for fitted garments |
Frequently Asked Questions
Can I pre-wash fabric in the dryer instead of the washing machine?
No. The dryer applies heat without water, so it will not remove loose dyes and may actually cause shrinkage without washing out the dye first. Always wash in water before drying.
What if I pre-wash and the fabric still shrinks after I sew it?
Some shrinkage can happen even after pre-washing, especially if you wash the finished garment in hotter water than you used to pre-wash. If you pre-washed in cold water and then wash the garment in warm water, additional shrinkage is possible. Wash the finished garment in the same temperature you used to pre-wash.
Do I need to pre-wash fabric if I am making a quilt?
Yes, especially if you are mixing light and dark fabrics. Dark fabric dye can bleed onto light squares during quilting and washing. Pre-wash all fabric, and if dark dye still bleeds in the pre-wash water, rinse it again until the water runs clear.
How do I know if fabric is pre-shrunk?
Check the bolt end (the paper label wrapped around the bolt) or ask the fabric seller. The label will say "pre-shrunk," "sanforized," or "shrink-resistant." If the label does not mention it, assume the fabric is not pre-shrunk.
Should I pre-wash interfacing?
Yes, if the interfacing is cotton or linen-based. Wash it in the same temperature as the fashion fabric so it shrinks at the same rate. Fusible interfacing (the kind you iron on) can usually skip pre-washing because the adhesive is stable, but check the package to be sure.