Fabric Shrinkage Predictor
Predict post-wash shrinkage before you cut.
45.8 × 63.2 in
Cut pre-wash so the piece settles to 44 × 60 in after a hot wash.
- Extra width to add
- 1.8 in
- Extra length to add
- 3.2 in
Tip: always pre-wash using the method you will launder the finished item with, then measure a swatch to confirm.
About This Tool
The Fabric Shrinkage Predictor works out the pre-wash cut size you need so a piece still measures your target after it has been washed and dried.
You enter the finished width and length you want, then the shrinkage percentages for each direction, or pick a fiber to load typical values.
It divides your target by one minus the shrink rate, giving the larger raw dimensions to cut before laundering.
The result shows the cut size and how many extra inches you are adding across and down the piece, so nothing comes out of the dryer too small.
Why Fabric Shrinkage Predictor Math Matters
Cotton, linen and flannel shrink most in their first hot wash, and the change is rarely equal across the width and the length.
Cut to the finished size and wash later, and a piece can come out a full inch small, spoiling a quilt block or a garment panel.
Predicting shrinkage up front means the item fits after it is laundered, not only when it leaves the sewing machine.
That reliability matters most for gifts, commissioned orders and group projects that will be washed again and again for years.
Getting the raw cut right also protects expensive fabric, because a shrunken panel cannot be stretched back to size once the fibers have contracted.
Accurate, tested shrink guidance is the sort of practical detail that builds trust with readers and with search engines alike.
The Formula
Cut size = finished size / (1 - shrink percent). The same calculation runs separately for width and length, because warp and weft shrink by different amounts.
- Finished size —
- the measurement you want to end up with after washing, in inches
- Shrink percent —
- how much the fabric contracts in that direction, entered as a whole number
- Cut size —
- the larger pre-wash measurement to cut so the piece lands on target
- Warp and weft —
- the lengthwise and crosswise grain, which almost never shrink by the same amount
The tool also reports the extra inches to add across and down, so you can mark the cut straight from the fabric selvage.
Worked Example: Step by Step
- 1Say you want a quilt panel that finishes at 44 inches wide by 60 inches long.
- 2You are using plain-weave cotton that shrinks about 4 percent across and 5 percent down.
- 3Divide the width target by 0.96, giving 45.8 inches to cut.
- 4Divide the length target by 0.95, giving 63.2 inches to cut.
- 5Cut the piece 45.8 by 63.2 inches, pre-wash it hot, and it settles close to 44 by 60.
- 6Press and square the grain before cutting your final pieces, so any remaining distortion is removed while the cloth is still flat.
- 7The extra 1.8 inches across and 3.2 inches down are exactly the buffer that keeps the block true after every later wash.
How to Use This Calculator
- Enter the finished width and length you want the piece to end up at.
- Pick a fiber to load typical shrink rates, or type your own percentages.
- Set width and length shrink separately, since the two grain directions differ.
- Read the cut size, then add the same margin to every matching pattern piece.
- Always test one swatch in your real wash and dryer before cutting a whole project.
Key Terms
- Shrinkage
- The contraction of a fabric after washing or steaming, expressed as a percentage of its original size.
- Pre-washing
- Laundering fabric before you cut so the shrink happens in the flat cloth rather than the finished piece.
- Warp
- The lengthwise grain running parallel to the selvage, which often shrinks more than the crosswise grain.
- Weft
- The crosswise grain running from selvage to selvage, usually shrinking slightly less than the warp.
- Relaxation shrink
- The small tightening that occurs when woven fabric gets wet and the yarns release loom tension.
- Squaring the grain
- Trimming the crosswise edges perfectly straight so cut pieces stay on-grain after shrinking.
- Dryer shrink
- the additional contraction driven by hot tumble drying rather than the wash water itself, often the bigger share of total shrink
Fabric Shrinkage Predictor Reference Table
| Fiber | Width shrink % | Length shrink % |
|---|---|---|
| Cotton (plain weave) | 4 | 5 |
| Linen | 6 | 8 |
| Denim | 3 | 4 |
| Flannel | 5 | 6 |
| Wool (washable) | 5 | 5 |
| Polyester | 1 | 1 |
Typical first hot-wash shrinkage by fiber. Real rates vary with weave, finish and dryer heat, so confirm against your own swatch before committing a full cut. Wool and linen move the most, while polyester barely changes, so weight the margin toward natural fibers.
Common Mistakes & Pro Tips
- Cutting to finished size and hoping for the best. Once the piece shrinks past your seam allowance there is no way to add fabric back.
- Washing the swatch differently from the finished item. If the quilt will be tumble-dried hot, test it hot, because a cold-wash swatch understates shrink.
- Assuming both grains shrink equally. Lengthwise warp often pulls in more than crosswise weft, so enter two numbers rather than one.
- Trusting a preshrunk label completely. Even quality quilting cotton can move one to two percent, enough to spoil a precise border or pieced point.
Real-World Use Cases
- Cutting quilt backing and borders that must stay square through many laundry cycles.
- Drafting table linens, cloth napkins and tea towels that are washed hot again and again.
- Sizing garment panels such as shirt fronts and collars where a single inch of shrink spoils the fit.
- Planning a batch of baby items and kitchen linens that will be machine-washed constantly.
- Ordering fabric for a commissioned run, where ordering a little extra prevents a mismatched dye lot later.
- Making a cotton dress or blouse that needs to keep its measurements after repeated home laundering.
Fabric Shrinkage Predictor: Frequently Asked Questions
Is preshrunk fabric already safe to cut at finished size?
Mostly, but not entirely. Preshrunk cotton can still move one to two percent, so cut a small margin and test one swatch in your real wash before trusting the label on the bolt.
Should I wash the whole project before cutting?
Yes, pre-wash and press the fabric exactly as the finished item will be laundered. Shrinking the flat cloth first means the piece you cut holds its size through every later wash.
Why are width and length shrinkage different?
Woven fabric sits under more tension lengthwise on the loom, so the warp grain usually contracts more than the weft. Entering two numbers reflects that real difference and keeps both grain directions true after the wash.
Does dryer heat matter as much as water temperature?
It matters a great deal. High dryer heat drives most of the shrink in cotton and wool, so test with the same heat you plan to use on the finished piece.
How do I find the exact shrink rate of my fabric?
Cut a marked square, measure it, then wash and dry it as you will the project. Measure again and the percentage you lost is the number to enter here for that fabric.
This page explains how the fabric shrinkage predictor works, what each input means and where the numbers come from, so you can plan your next make with confidence.
Written by Bobbin & Form Editorial Team
Home sewists & machine-embroidery practitioners
Reviewed by Marie Delacroix
Custom sewist & machine-embroidery technician, 15 years at the machine
Formulas follow standard sewing and needlework references. Results are estimates — always confirm against your pattern and a pre-washed swatch.
Sources & further reading
- Threads Magazine — fabric cutting & yardage guides
- ISO 13934 — textile tensile & fabric property standards
- Your local fabric store's bolt-width charts