Most fabric shrinks the first time it is washed, and how much depends mainly on the fiber and on how loosely it is woven or knitted. As a rule of thumb, expect 2–5 % from cotton, linen and viscose wovens, 5–10 % from loose or brushed fabrics such as flannel, double gauze and cotton jersey, under 2 % from polyester and nylon, and anything from very little to a felted disaster from wool, depending on how it is washed. Buy about 10 % more fabric than the pattern asks for, pre-wash it the way you will wash the garment, and shrinkage stops being a problem before you cut.
Why does fabric shrink?
Three things happen in the first wash. The first is relaxation: yarns are held under tension while they are woven, knitted and finished, and water lets them relax back to a shorter length. This is why fabric usually shrinks more along its length (the warp, parallel to the selvedge) than across its width.
The second is fiber swelling. Cellulose fibers such as cotton, linen and viscose absorb water, swell, and pull the yarns into a tighter crimp; when they dry, the fabric is a little shorter. The third is felting, which only concerns animal hair fibers: wool fibers have microscopic scales that lock together under heat, moisture and agitation, which is how a sweater ends up child-sized after a hot machine wash.
Heat makes all three worse. A hot wash and a tumble dryer pull out more shrinkage than a cool wash and a line dry, which is why the rule is to pre-wash exactly as you plan to wash the finished garment.
How much does each fiber shrink?
The figures below are typical ranges for the first wash of untreated fabric. Your bolt may land outside them, especially if it is loosely woven, heavily brushed or cheaply finished, so treat them as a planning guide rather than a promise.
| Fiber or fabric | Typical first-wash shrinkage | Notes |
|---|---|---|
| Cotton woven (poplin, lawn, twill, denim) | 2–5 % | Mostly in length; denim can be at the top of the range |
| Cotton knit (jersey, interlock, French terry) | 3–8 % | Lengthwise; relaxes more after a tumble dry |
| Cotton flannel, double gauze, loosely woven cotton | 5–10 % | Pre-wash twice to be safe |
| Linen | 3–6 % | Loose linens shrink more and soften a lot |
| Viscose and rayon | 3–8 % | Some challis shrink more; handle gently while wet |
| Lyocell (Tencel) and modal | 2–4 % | More stable than viscose |
| Wool woven (suiting, flannel, crepe) | 2–5 % with a cool hand wash or steam | Felts and shrinks far more if washed hot and agitated |
| Silk | 1–3 % | Crepe and gauze weaves can shrink more |
| Polyester, nylon, acrylic | 0–2 % | Shrinkage is usually relaxation only |
| Blends | In between | Follow the dominant fiber, then test |
"Pre-shrunk" and "sanforized" on a label mean the mill has already pulled most of the relaxation out, usually to 1 % or so. It is still worth washing those fabrics once to remove finishing chemicals and check that the dye is stable.
Does the weave or knit change how much fabric shrinks?
Yes, often more than the fiber does. A tightly woven cotton poplin has little room to move, so it shrinks at the low end of the range. A loosely woven cotton gauze or a brushed flannel has slack between the yarns and shrinks at the high end. The same applies to knits: a dense interlock is more stable than a light, open jersey of the same fiber.
Knits also shrink more in length than wovens do, because the loops are stretched lengthwise when the fabric is rolled onto a bolt. Dry a cotton jersey in a tumble dryer and the loops pull back into their relaxed shape, which can be 5 cm (2 in) less on every meter. Knit fabric bought for a T-shirt should therefore always be washed and dried before cutting, or the finished tee ends up short after its first wash.
Does fabric shrink more in length or in width?
Mostly in length. The warp yarns run under tension on the loom and are stretched again on the stenter frame during finishing, while the weft is held only by the pins along the selvedge. In practice a cotton woven might lose 4 % in length and 1–2 % in width. Linen and viscose follow the same pattern.
This matters for planning. A pattern that needs 2 m (2 1/4 yd) of fabric loses 8 cm (3 1/8 in) of usable length at 4 % shrinkage, which is roughly the difference between fitting a long sleeve on the layout and not. Width loss is small enough to ignore unless you were counting on every centimeter of a 110 cm (45 in) fabric.
How much extra fabric should you buy for shrinkage?
Add 10 % to the quantity the pattern gives you for cotton, linen, viscose and knits, and 15 % for flannel, double gauze, loosely woven linen and anything sold as unwashed denim. Polyester and other synthetics need no allowance beyond a little extra for straightening the ends.
In practice:
- 1.5 m (1 5/8 yd) on the pattern becomes about 1.7 m (1 7/8 yd).
- 2.5 m (2 3/4 yd) becomes about 2.8 m (3 yd).
- 3 m (3 1/4 yd) of flannel becomes about 3.5 m (3 3/4 yd).
Many shops cut in 10 cm or 1/8 yd steps, so round up rather than down. If you draft a pattern in Sewly, the sewing guide lists fabric quantities for 110, 140 and 150 cm (45, 55 and 60 in) wide fabric; add your shrinkage margin on top of the figure for your width. The fabric yardage calculator does the same arithmetic for other patterns, and how much fabric do I need explains how quantities are worked out in the first place.
How do you pre-wash fabric so it shrinks before you cut?
Wash it as you will wash the garment: same temperature, same detergent, same drying. If the finished dress will go through a 40 °C (105 °F) wash and a tumble dryer, that is what the fabric gets before cutting. Serge or zigzag the cut ends first on loosely woven fabrics, or they fray into a tangle of threads in the drum.
Dry knits flat or in the dryer rather than on a line, where their own weight stretches them. Press everything while slightly damp, on the grain, without pulling, and let it cool flat. The pre-washing fabric guide goes through the details for each fabric family, including which ones should be steamed rather than washed.
Flannel, double gauze and cotton jersey are the fabrics that keep shrinking after the first wash. If you are sewing something that must stay the same size, such as fitted trousers, wash them twice.
How do you measure how much your fabric actually shrinks?
When the exact figure matters, measure it. Before washing, mark a square on the fabric with a contrasting basting thread, 50 cm (20 in) on each side, with the edges along the grain. Wash and dry the whole piece as planned, press it, and measure the square again.
If the lengthwise side now measures 48 cm, the fabric has shrunk 4 % in length; if the crosswise side measures 49.5 cm, 1 % in width. Keep the numbers with your fabric notes: they tell you how much to buy next time from the same shop, and they are the figure to use if you ever have to cut without pre-washing and want to lengthen the pattern to compensate.
A quicker version uses a 20 × 20 cm (8 × 8 in) swatch washed on its own, which is handy for deciding whether to buy more of a fabric before the shop sells out.
What if you cannot pre-wash the fabric?
Some fabrics should not go in the machine: dry-clean-only wool, many silks, coated fabrics and anything with a finish you want to keep. For wool and silk, the standard alternative is steam shrinking. Hover a steam iron 1–2 cm (1/2–3/4 in) above the fabric, without touching it, and move slowly across the whole piece; let it dry and cool flat before you cut. Wool can lose 2–3 % this way and will then stay stable through dry cleaning and careful pressing.
For fabric you have already cut without washing, there is no going back, so sew the garment and wash the finished piece gently in cool water. Fusible interfacing is the one component people forget: it can shrink separately from the fabric and bubble after the first wash. Soak it in warm water, let it drip dry, and it behaves.