Fabric Shrinkage Calculator
Buying the right amount of fabric requires accounting for shrinkage before you cut your pattern pieces. Most natural fibres shrink when first washed and dried, and cutting before pre-washing produces a finished project that is smaller than intended. The standard approach is to calculate how much fabric you need after shrinkage, then work backwards to find how much to purchase from the bolt. The formula is straightforward: divide your desired finished yardage by one minus the shrinkage rate expressed as a decimal. For example, if you need 3 yards of finished cotton fabric and expect 4 percent shrinkage, you should buy 3 divided by 0.96, which equals about 3.13 yards. Width matters too: if the bolt shrinks below your required cut width, you will need to buy more length to make up the difference. This calculator covers cotton, linen, wool, silk, polyester, rayon or viscose, denim, and bamboo, with industry-typical default shrinkage rates for each fibre. You can override the shrinkage percentage for your specific fabric after running a personal shrinkage test on a sample square.
Buy at least -- yards of fabric before washing
Shrinkage formula
Both length and width use the same calculation:
pre_wash_length = desired_finished_length / (1 - shrinkage_rate / 100) pre_wash_width = desired_finished_width / (1 - shrinkage_rate / 100) extra_yardage = pre_wash_length - desired_finished_length
Example: you need 3 yards of finished cotton fabric and expect 4% shrinkage.
pre_wash_length = 3 / (1 - 0.04) = 3 / 0.96 = 3.125 yards
Buy at least 3.13 yards (round up to the nearest eighth-yard when purchasing).
Typical shrinkage rates by fiber type
These rates are industry estimates. Your fabric may vary. Always pre-test a sample if precision is critical.
| Fiber type | Typical range | Default used | Notes |
|---|---|---|---|
| Cotton | 3%–5% | 4% | Pre-wash on warm; tumble dry medium |
| Linen | 3%–4% | 3.5% | May feel softer after washing |
| Wool | 5%–10% | 7% | Use cold water or hand-wash to minimise felting |
| Silk | 2%–4% | 3% | Dry-clean-only silks may not need pre-washing |
| Polyester | 0%–1% | 0.5% | Minimal shrinkage; still recommended to pre-wash |
| Rayon / Viscose | 3%–10% | 6% | Can shrink significantly; air-dry recommended |
| Denim | 3%–10% | 5% | Sanforised denim shrinks less (typically 1%–3%) |
| Bamboo | 4%–6% | 5% | Similar care to cotton |
Note on width: bolt widths are typically 44 inches for quilting cottons and 60 inches for apparel fabrics. After washing, the usable width may decrease. If the pre-wash width your project requires is close to or exceeds the bolt width, buy extra length to compensate for selvedge trimming.
Fabric shrinkage: frequently asked questions
Why does fabric shrink when washed?
Fabric shrinks because fibres that were stretched during weaving or knitting relax when exposed to heat and water. Natural fibres such as cotton, linen, and wool absorb moisture and swell, then contract as they dry. The degree of shrinkage depends on the fibre type, yarn structure, weave, and finishing treatments applied during manufacturing. Pre-washing fabric before cutting eliminates most of this shrinkage so your finished project retains its intended dimensions.
What is a typical shrinkage rate for cotton?
Cotton fabric typically shrinks 3 to 5 percent in length after the first wash, with an average of around 4 percent widely used for planning purposes. Some loosely woven cottons or unwashed muslins may shrink up to 10 percent. Pre-shrinking by washing and drying on high heat before cutting is standard practice for quilting and garment sewing projects.
Should I pre-wash all fabrics before sewing?
Pre-washing is recommended for most natural-fibre fabrics (cotton, linen, wool) and for any fabric that will be laundered after the project is finished. Dry-clean-only fabrics such as some silks and wools do not need pre-washing if the finished item will always be dry cleaned. Interfacings, stabilisers, and notions should also be pre-washed to match the behaviour of the fashion fabric.
How do I measure my fabric's actual shrinkage rate?
Cut a 10-inch by 10-inch square of your fabric. Measure and mark it precisely, then wash and dry it the same way you plan to launder the finished project. Measure again after drying. Divide the change in length by the original length and multiply by 100 to get the percentage. Use this measured rate in the calculator for the most accurate result.
Does fabric shrink in width as well as length?
Yes. Fabric can shrink in both the lengthwise (warp) and widthwise (weft) directions, though shrinkage is often greater along the length. This calculator lets you enter your desired finished width so you can confirm the pre-washed bolt width is sufficient. Fabric that shrinks below your required cut width will require a wider bolt or a pattern adjustment.
Sources and methodology
- ASTM D3512 standard for fabric shrinkage testing: ASTM International.
- Fiber shrinkage ranges derived from textile industry standards and manufacturer care guidelines.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. Shrinkage rates are typical estimates; always test your specific fabric. See our methodology.