Prewashing stops your finished garment from shrinking after you wear it

Prewash fabric the same way you plan to wash the finished garment. If you will hand-wash your dress, hand-wash the fabric. If it goes in the machine on warm, wash it on warm. This prevents the surprise of a fitted shirt that no longer fits after the first real wash.

Most natural fabrics shrink: cotton, linen, wool, and rayon all lose size when wet. Synthetics like polyester and nylon shrink less, but blends behave unpredictably. Prewashing before cutting means you shrink the yardage, not the finished piece. A garment that shrinks after you sew it is ruined. Fabric that shrinks before you cut it is straightforward smaller — you adjust your pattern or buy extra yardage.

Prewashing also removes finishes manufacturers explore to keep fabric crisp on the bolt, and it sets dyes so they do not bleed onto other fabrics later. The time you spend now saves you from a garment that fits wrong or stains your other clothes in the wash.

Key Takeaways

  • Wash fabric in the same temperature and method you will use on the finished garment, because different conditions produce different amounts of shrinkage.
  • Dry fabric the same way too — machine drying shrinks more than air drying, so if you plan to air-dry the garment, air-dry the fabric.
  • Prewash natural fibers like cotton, linen, and rayon; skip it for most synthetics unless the bolt label warns of shrinkage or dye bleeding.
  • Measure fabric before and after washing to know how much it shrank, so you can adjust yardage or pattern size if needed.
  • Press fabric after it dries to remove wrinkles before you lay out your pattern, or the wrinkles will throw off your cutting.

Wash fabric in the temperature and cycle you will actually use

Check the bolt label for fiber content and any care instructions the manufacturer printed. This tells you what the fabric can handle. If the label says "warm water" or "gentle cycle," follow that. If there is no label, assume natural fibers need cool or warm water and synthetics can take warm or hot.

The key is matching your prewash to your real wash. If you plan to machine-wash your finished garment in hot water, wash the yardage in hot water. If you will hand-wash it in cool water, hand-wash the yardage in cool water. Shrinkage happens at different rates depending on temperature. A fabric that shrinks 2 percent in warm water might shrink 5 percent in hot water. Prewashing in the wrong temperature gives you a false result.

Use the same detergent you will use on the finished garment, or at least the same type — gentle detergent for delicates, regular for everyday wear. Rinse until the water runs clear, especially with dark fabrics, because excess soap left in the fibers can affect how dye sets.

Dry fabric the same way you will dry the garment

Machine drying shrinks fabric more than air drying. If you plan to air-dry your finished dress, air-dry the yardage. If you will tumble-dry it, tumble-dry the fabric. Mixing methods — washing in one way and drying in another — gives you incomplete information about how much the fabric will actually shrink in real use.

For machine drying, use the same heat setting you plan to use on the garment. High heat shrinks more than low heat. Delicate fabrics like rayon and linen often need low heat or air drying to avoid damage, so prewash them on a gentle cycle and dry them on low or hang them to dry.

If you air-dry, hang the fabric on a clothesline or lay it flat on a clean surface. Do not wring it hard — gently squeeze out excess water. Wringing can stretch the fabric unevenly and create permanent wrinkles that are hard to press out later.

Measure before and after to track shrinkage

Write down the length and width of your fabric before you wash it. Measure along the grain, not diagonally. Use a measuring tape and write the numbers down — do not rely on memory.

After the fabric dries completely, measure it again in the same direction. The difference is your shrinkage. If a piece of cotton was 45 inches wide and is now 44 inches wide, it shrank 1 inch, or about 2 percent. If you need 2 yards of fabric for your pattern and the fabric shrank 2 percent, you should buy 2.1 yards instead.

Write the shrinkage percentage on a piece of tape and stick it to your pattern or keep it in your sewing notebook. If you use the same fabric again, you already know what to expect. Over time, you will recognize which fabrics shrink a lot and which barely shrink at all, and you can adjust your yardage purchase before you even bring the fabric home.

Press fabric after drying to remove wrinkles before cutting

Wrinkles in fabric throw off your pattern layout and your cutting. A wrinkle that looks small can shift your grain line and make a piece cut slightly off-grain, which causes the finished garment to hang wrong or twist at the seams.

Use an iron on the setting appropriate for your fiber. Cotton and linen take high heat. Rayon and synthetics need medium heat. Silk needs low heat or a pressing cloth between the iron and the fabric. Press with the grain when possible, moving the iron in the direction the fibers run, not against them.

If the fabric is very wrinkled, dampen it lightly with a spray bottle before pressing, or use a steam iron. Let the fabric cool and dry completely before you fold it or lay out your pattern. Folding warm fabric can set new wrinkles into it.

Fabrics that do not need prewashing

Most synthetic fabrics — polyester, nylon, acrylic — shrink very little and do not bleed dye. If the bolt label does not warn of shrinkage or dye issues, you can skip prewashing. Blends that are mostly synthetic (80 percent polyester, 20 percent cotton, for example) usually do not need prewashing either, though checking the label takes 10 seconds and costs nothing.

Specialty fabrics like velvet, corduroy, and pile fabrics can be damaged by washing. Check the label. If it says "dry clean only," do not prewash — take the finished garment to the dry cleaner instead. If it says "hand wash," you can prewash by hand in cool water and lay it flat to dry.

Knit fabrics sometimes need special handling. Delicate knits can stretch or lose shape in the wash. If you are working with a fine knit, wash it gently by hand in cool water and lay it flat to dry, or use the delicate cycle on your machine with cool water.

What to do if fabric shrinks more than expected

If your fabric shrank more than you anticipated and you do not have enough yardage for your pattern, you have a few options. The simplest is to buy more fabric from the same dye lot if the store still has it. Dye lots can vary in color, so match the bolt number if possible.

If you cannot buy more, you can adjust your pattern. Grade the pattern down one size if the shrinkage is small (under 3 percent). If it is larger, you may need to choose a smaller pattern size or a different pattern altogether. Some sewers use the extra yardage for a smaller version of the garment — a child's version of an adult pattern, for example.

Keep the prewashed fabric in a dry place until you are ready to cut. Do not leave it damp or in a humid space, because it can develop mildew or mold, especially if it is natural fiber.

Frequently Asked Questions

Do I have to prewash cotton and linen?

Cotton and linen shrink noticeably — usually 2 to 5 percent — so prewashing is worth the time. The only exception is if you are making something you do not mind shrinking, like a dish towel or a work apron. For fitted garments like shirts and pants, prewash.

What if I prewash and the fabric still shrinks after I sew it?

This usually means you washed or dried the fabric differently than you will wash the finished garment. If you hand-washed the yardage but plan to machine-wash the shirt, the shirt will shrink more. Wash and dry the fabric the exact same way you plan to treat the finished piece.

Can I prewash fabric that has a pattern printed on it?

Yes, but use cool water and gentle detergent. Printed patterns can fade or bleed, especially on dark backgrounds. Wash it once in cool water, check whether the color runs, and if it does, rinse it in cool water until the water is clear. Air-dry printed fabric rather than machine-drying it, because heat can set any remaining loose dye.

How long does prewashing take?

Washing takes 20 to 40 minutes depending on your machine cycle. Drying takes 30 minutes to several hours depending on whether you machine-dry or air-dry. Plan to prewash fabric at least a day or two before you want to cut, so you have time to wash, dry, and press without rushing.

Should I prewash fabric I bought online?

Yes, especially if you do not know the fiber content or care instructions. Online sellers sometimes do not list shrinkage information, so prewashing tells you what to expect. It also removes any dust or handling residue from shipping.