Fabric Shrinkage Calculator: The Short Answer
A brand marks a 50 by 50 centimetre square on a fabric swatch and washes it. Afterwards the square measures 47.5 centimetres in length and 48.5 centimetres in width. The fabric shrinkage calculator turns those readings into 5 per cent shrinkage in length and 3 per cent in width, which means about 7.9 per cent of the fabric area is lost. It also answers the question that matters on the cutting table: to finish a body 70 centimetres long after a 5 per cent length shrink, the panel must be cut at 73.7 centimetres, and a 52 centimetre chest needs 53.6 centimetres cut at a 3 per cent width shrink.
The readings in this example are illustrative. Your own fabric will shrink by a different amount, which is why the test comes first and the calculation second. A fabric shrinkage calculator is only as reliable as the measurements fed to it.
Use the Fabric Shrinkage Calculator
Mark a square on a swatch, measure it flat and relaxed, wash and dry the swatch the way a customer would, let it relax, and measure the same marks again. Enter the lengths and widths before and after. If you want the cutting allowance, add the finished garment length and chest width you are aiming for. The fabric shrinkage calculator returns the shrinkage in each direction, the area lost, and the cut size needed.
Fabric shrinkage calculator
Shrinkage and cut size
Marked swatches need measuring flat and relaxed, before and after the same wash. A swatch test is a guide, not a certified laundering result.
A negative result in the fabric shrinkage calculator means the fabric grew, which happens with some stretchy or relaxed constructions. It is still information: the garment will finish larger than it was cut, and you may need to cut smaller. Run the same test on more than one swatch to see how consistent the fabric is.
How Shrinkage Is Calculated
Shrinkage is the change in a measurement as a share of the original. Subtract the after measurement from the before measurement, divide by the before measurement and multiply by 100. Do it separately for length and width, because fabric rarely shrinks the same amount both ways. Area shrinkage combines the two: it is one minus the product of the remaining fractions.
Worked example from the swatch test
| Direction | Before washing | After washing | Shrinkage |
|---|---|---|---|
| Length | 50.0 cm | 47.5 cm | 5.0% |
| Width | 50.0 cm | 48.5 cm | 3.0% |
| Area | 2,500 cm² | 2,304 cm² | 7.9% |
Illustrative readings. Shrinkage = (before − after) ÷ before. Area uses the product of the two dimensions.
Standards bodies including the AATCC and the ISO publish laundering and dimensional change methods that laboratories follow for certified results. A home swatch test is a useful check, but it does not replace one when a specification or a retailer calls for it.
How Much Larger Should You Cut?
The cutting rule is to divide the finished size by one minus the shrinkage. A 5 per cent shrink does not mean cutting 5 per cent larger, because the 5 per cent is taken from the larger cut piece, not from the finished one. Adding the percentage cuts the garment slightly too small, and the error grows with the shrinkage.
Cut length needed for a 70 cm finished body
| Shrinkage | Adding the percentage | Dividing (correct) | Difference |
|---|---|---|---|
| 2% | 71.4 cm | 71.4 cm | 0.0 cm |
| 3% | 72.1 cm | 72.2 cm | 0.1 cm |
| 5% | 73.5 cm | 73.7 cm | 0.2 cm |
| 8% | 75.6 cm | 76.1 cm | 0.5 cm |
| 10% | 77.0 cm | 77.8 cm | 0.8 cm |
Calculated as 70 ÷ (1 − shrinkage) against 70 × (1 + shrinkage). Illustrative finished length and shrinkage.
At 2 per cent the shortcut is less than a millimetre out, which is why people get away with it. At 10 per cent it is about 8 millimetres short, and across a size range that is enough to push a garment into the next size. Use the division every time.
What Shrinkage Does to the Finished Chest
Width shrinkage works in the same way. A panel cut at the finished chest width ends up narrower after washing, and the table shows by how much for a 52 centimetre flat chest.
Finished chest width after shrinkage if cut at 52 cm
| Width shrinkage | Finished flat chest |
|---|---|
| 0% | 52.0 cm |
| 2% | 51.0 cm |
| 3% | 50.4 cm |
| 5% | 49.4 cm |
Calculated as 52 × (1 − shrinkage). Illustrative chest width and shrinkage.
A 3 per cent width shrink takes about 1.6 centimetres off a flat chest, which is roughly 3 centimetres off the circumference. That can be close to a full size step on many size charts. Our guide to reducing garment returns from fit and shrinkage explains why this matters commercially.
How Length and Width Combine
Shrinkage in both directions compounds, so the area lost is a little less than the two percentages added together. The chart shows five combinations from mild to severe.
Fabric area lost for different length and width shrinkage
Area lost (%)
Arithmetic: area lost = 1 − (1 − length shrinkage) × (1 − width shrinkage). Illustrative combinations.
A fabric that loses 5 per cent in both directions loses nearly 10 per cent of its area. That is the sort of change a customer notices after one wash. Test the fabric you will actually buy, and use the fabric consumption calculator to see how a larger cut size changes the fabric you need.
What Is Left of the Fabric in the Example?
In the swatch example, 7.85 per cent of the area disappears in the wash. The pie shows the share that is kept and the share that is lost.
Share of fabric area kept and lost in the swatch example
- Area kept (92.15%)92.2%
- Area lost to shrinkage (7.85%)7.8%
Arithmetic: 47.5 × 48.5 = 2,303.75 cm² against 2,500 cm² before washing. Illustrative readings.
Most of the swatch survives, but the loss is the part that changes how the garment fits. A cut size that does not allow for it produces a garment that is smaller than its label, which our guide to garment testing for shrinkage and colour fastness covers.
Why Shrinkage Matters More Than It Looks
Shrinkage is a quiet cost. A garment that shrinks beyond what the size chart allows is returned, reviewed badly or worn once and discarded, and none of those costs appear on the factory quote. The fabric shrinkage calculator turns a vague worry into a number you can act on before cutting, when changing the pattern is cheap.
It also gives you a basis for a conversation with the supplier. A fabric that shrinks 8 per cent in length is a different product from one that shrinks 3, and the price difference between them is usually smaller than the cost of the returns. Asking for shrinkage figures in both directions, from the bulk fabric, is a reasonable request from any buyer.
Shrinkage and the Rest of the Costing
A larger cut size uses more fabric. If a pattern needs to grow by 5 per cent in length to finish on size, the fabric per garment rises by roughly the same share, and that belongs in the budget. Feed the new cut dimensions into the fabric consumption calculator rather than guessing, and compare the result with the cost of choosing a more stable fabric.
Pre-shrunk or compacted fabrics, where the mill has already taken out most of the shrinkage, usually cost more per metre but need a smaller allowance and carry less risk. Whether that trade is worthwhile depends on the garment and the price point, and a shrinkage test on each candidate fabric is the evidence to decide with.
Steps for a Reliable Shrinkage Test
A shrinkage test is simple, but the details decide whether it is useful. Follow the same steps every time so results can be compared.
Running a swatch test
- 1Cut a swatchAt least 50 × 50 cm from the body of the roll, not the edge.
- 2Mark itDraw a measured square with fabric-safe marks in length and width.
- 3Measure beforeFlat, relaxed and unstretched; record to the millimetre.
- 4Wash and dryAs the care label says; use the same method each time.
- 5Relax and measureFlat and unstretched, and record the same marks.
- 6CalculateShrinkage in each direction, then the cut allowance.
Twisting, also called skew, is a separate problem that shrinkage figures do not capture. If side seams spiral after washing, the fabric needs a different finish or construction. Our guide to stopping hoodie shrinkage, twisting and fit changes goes through it.
Checks Before You Cut Bulk Fabric
A short list keeps shrinkage from becoming a surprise on the finished garment.
Shrinkage checks before bulk cutting
- Test the bulk fabric, not just the sample fabric
- Measure length and width separately
- Use the cut-size division, not the added percentage
- Repeat the test on more than one roll or lot
- Ask whether the fabric has been pre-shrunk or compacted
- Agree an acceptable shrinkage tolerance in writing
A general checklist. Certified test methods follow the relevant standard.
Returns for fit are expensive, and the return rate calculator shows what they cost a brand. A shrinkage test that costs a few pounds is cheap by comparison.
How Ruhrose Helps You Manage Shrinkage
Ruhrose develops hoodies, fleece, jersey, denim and woven casualwear for UK buyers, with production in Bangladesh. We sample before bulk, test fabric where it matters and explain how shrinkage is allowed for in the pattern, so the finished garment matches the size you approved. Ruhrose's clothing manufacturing pages show what we make.
Before you approve a fabric, ask yourself one question: has anyone washed it and measured it twice?