Fabric Shrinkage Calculator
Divide by what is left, do not add the percentage back. At 20% shrinkage that mistake leaves you 3.6 inches short.
Measure your own instead
Cut a square, mark it, wash it exactly as you will the garment, and measure again. Ten minutes beats any table.
Divide by what is left, do not add the percentage back
A shrinkage figure is measured against the original length, so fabric that shrinks 10 per cent keeps 90 per cent of what you bought. To finish with 2 yards you need 2 ÷ 0.90 = 2.222, not 2 × 1.10 = 2.200. Adding the percentage back always comes up short.
| Shrinkage | Divide (correct) | Add back (wrong) | Short by |
|---|---|---|---|
| 2% | 2.041 yd | 2.040 yd | 0.03 in |
| 5% | 2.105 yd | 2.100 yd | 0.19 in |
| 10% | 2.222 yd | 2.200 yd | 0.80 in |
| 15% | 2.353 yd | 2.300 yd | 1.91 in |
| 20% | 2.500 yd | 2.400 yd | 3.60 in |
The shortfall is exactly target × s² ÷ (1 − s) — not an approximation, and the two methods agree only at zero. At 2 per cent it is a rounding error you would never notice. At 20 per cent it is three and a half inches, which on a two-yard cut is the difference between a garment and an offcut.
A square does not shrink to a square
Lengthwise shrinkage almost always exceeds crosswise, because the lengthwise grain is held under tension all through finishing and relaxes the first time it is washed. Cotton jersey typically moves about 8 per cent along the grain and 4 across.
Which means a 36 inch square comes out 33.1 by 34.6 — no longer square, and out by nearly an inch and a half on a piece you would have cut as one. It also means a garment pre-cut without pre-washing does not just get smaller, it changes shape: shorter in the body more than it narrows.
Typical shrinkage
Starting points for fabric you have not tested. Real figures vary by mill, weave and finish, so a measured square always wins.
| Fabric | Lengthwise | Crosswise | |
|---|---|---|---|
| Cotton, woven (quilting, poplin) | 3% | 2% | Pre-shrunk goods move less; unbleached and unwashed cotton moves considerably more. |
| Cotton flannel | 6% | 4% | Brushed surfaces shrink more than the same fibre woven flat. |
| Cotton jersey / knit | 8% | 4% | Knits relax a great deal lengthwise. Wash twice before cutting anything fitted. |
| Linen | 8% | 5% | Shrinks hard on the first wash and keeps moving a little for several more. |
| Rayon / viscose | 10% | 6% | One of the worst. Test a sample before committing anything you care about. |
| Wool, woven | 4% | 3% | Steam rather than wash. Untreated wool will felt if agitated in hot water. |
| Denim | 5% | 3% | Raw denim shrinks far more; sanforised denim far less. |
| Polyester and blends | 1% | 1% | Barely moves, which is most of the reason it is used. |
Just pre-wash it
All of this arithmetic exists for the cases where you cannot pre-wash — dry-clean-only wool, anything with a finish that washing would ruin, or fabric you are cutting straight off the bolt. Where you can wash first, do: wash and dry it exactly the way the finished thing will be treated, twice for knits and linen, and then the fabric in front of you is the fabric you will keep. Buying extra to allow for shrinkage and then also pre-washing means buying twice.
How to use
- Enter the finished length you need after washing.
- Pick a fabric or enter your own measured shrinkage.
- Measure both directions separately — they are not the same.
- Better still, cut a square, wash it, and measure what actually happened.
Frequently asked questions
How much extra fabric should I buy for shrinkage?
Divide the finished length by one minus the shrinkage, rather than adding the percentage back on. Fabric that shrinks 10 per cent keeps 90 per cent of what you bought, so 2 yards finished needs 2 divided by 0.90, which is 2.222 yards — not 2 times 1.10, which is 2.200 and leaves you short.
How wrong is adding the percentage back?
Exactly the target times s squared over one minus s, where s is the shrinkage. At 2 per cent that is a rounding error nobody would notice. At 20 per cent on a two-yard cut it is three and a half inches, which is the difference between a garment and an offcut. The two methods agree only at zero shrinkage.
Does fabric shrink the same in both directions?
No, and the difference matters. Lengthwise shrinkage almost always exceeds crosswise, because the lengthwise grain is held under tension all through finishing and relaxes the first time it is washed. Cotton jersey typically moves about 8 per cent along the grain and 4 across.
So a square does not stay square?
Correct. A 36 inch square of cotton jersey comes out about 33 by 34.6 — out by more than an inch and a half. It also means an unwashed garment does not simply get smaller when you wash it, it changes proportion, becoming shorter in the body more than it narrows.
How do I measure my own shrinkage?
Cut a generous square, mark a known distance in each direction with a pen or a line of stitching, wash and dry it exactly as you will treat the garment, then measure the marks again. Ten minutes gives you a figure for the fabric actually in front of you, which beats any table.
Should I just pre-wash instead?
Almost always yes, and then none of this arithmetic is needed. Wash and dry the fabric the way the finished thing will be treated — twice for knits and linen — and what is left is what you keep. Buying extra for shrinkage AND pre-washing means buying twice over.
When can I not pre-wash?
Dry-clean-only wool, anything with a finish that washing removes, silk that would water-mark, and fabric being cut straight off the bolt for something that will never be washed. Those are the cases this calculator is for; everywhere else the washing machine is the better tool.
Which fabrics shrink most?
Rayon and viscose are among the worst, at roughly 10 per cent lengthwise, followed by linen and cotton knits at about 8. Polyester barely moves at 1 per cent, which is a large part of why it is used. Any figure varies by mill, weave and finish, so treat published numbers as a starting point.
Does washing twice help?
For knits and linen, yes. Both keep moving on the second and sometimes third wash rather than doing it all at once, so a garment cut after a single wash still shrinks afterwards. Two washes before cutting removes most of that, and is why the advice is standard for those fibres.
Does the width shrink too?
Yes, which is easy to forget when the pattern says it needs 44 inch fabric. A 44 inch bolt at 3 per cent crosswise finishes about 42.7, and a pattern piece that only just fitted the width will not fit after washing. Check pieces against the washed width rather than the label.
What about hot water and tumble drying?
They increase shrinkage substantially, particularly for cotton and wool. The important thing is consistency: pre-wash the way you will launder the garment. Pre-washing cold and then washing the finished thing hot puts the shrinkage back exactly where you were trying to avoid it.
Does this send anything anywhere?
No. Everything is calculated in your browser and nothing is stored or uploaded.
🔒 This tool runs entirely in your browser. Nothing you enter is uploaded, logged, or stored.