Fabric Shrinkage Calculator
Wash a test piece and enter its size before and after, or pick a fiber type for a typical figure. The calculator gives the lengthwise and widthwise shrinkage and how much fabric to buy so you still have enough after pre-washing.
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Measure along the selvage (lengthwise grain).
Across the fabric (crosswise grain).
Typical rates for a first hot-ish wash and tumble dry; real fabrics vary with weave and finish.
What your pattern calls for, in finished (washed) fabric.
Optional: checks the washed width is still enough.
Optional extra for straightening the grain or cutting errors.
How to use the Fabric Shrinkage Calculator
- Wash a test piece (for example 10" × 10") exactly as you will wash the finished item, then dry and press it.
- Enter the sizes before and after, or switch to the fiber type estimate if you have not tested yet.
- Enter the length your pattern needs after washing, in yards or meters, and the bolt width.
- Add a safety margin if you like, then press Calculate shrinkage.
- Buy the rounded-up length shown and check the washed width is still wide enough.
Fabric shrinkage formulas
- Shrinkage % = (before − after) ÷ before × 100, measured separately for length and width
- Length to buy = length needed ÷ (1 − shrinkage) × (1 + safety margin)
- Washed width = bolt width × (1 − widthwise shrinkage)
- Area shrinkage = 1 − (1 − length %) × (1 − width %)
Example: a 10" × 10" cotton swatch measures 9⅝" × 9¾" after washing. That is 3.75% shrinkage lengthwise and 2.5% widthwise. To end up with 3 yards you need 3 ÷ 0.9625 = 3.117 yards, so buy 3⅛ yards. A 44" bolt will be about 42.9" wide after washing.
Note the formula divides rather than adds: adding 4% to 3 yards gives 3.12 yards, but 4% shrinkage of 3.12 yards leaves only 2.995 yards. Dividing by (1 − shrinkage) always leaves exactly what you need.
Typical shrinkage by fabric type
These are rough, typical ranges for a first wash and tumble dry. Weave, finishing, water temperature and dryer heat change the result, so treat them as a starting point and test a swatch for anything important.
| Fabric | Typical shrinkage | Notes |
|---|---|---|
| Quilting cotton | 2–5% | Often more lengthwise than widthwise |
| Cotton flannel | 4–10% | Brushed, loosely woven; pre-wash in hot water |
| Cotton jersey knit | 3–8% | Shrinks in length, may widen slightly |
| Raw (unsanforized) denim | 5–10% | Soak before cutting |
| Sanforized denim and shirting | 1–3% | Pre-shrunk at the mill |
| Linen | 3–5% | Can be more on loosely woven linen |
| Rayon / viscose | 3–8% | Wash cool; can also stretch when wet |
| Wool | varies | Hot water and agitation cause felting, which can shrink it a lot |
| Polyester, nylon | 0–1% | Very stable unless exposed to high heat |
How to test a swatch
- Cut a square at least 10" (25 cm) on the grain and mark the lengthwise direction.
- Measure it flat and write the sizes down; for accuracy, draw a 10" square with a fabric pen and measure the lines.
- Wash and dry it exactly as you will treat the finished item (same temperature and dryer setting).
- Press without stretching, measure again and enter both sets of numbers above.
Frequently asked questions
How do you calculate fabric shrinkage?
Shrinkage % = (size before washing − size after washing) ÷ size before washing × 100. Measure lengthwise and crosswise separately: a 10" piece that measures 9⅝" after washing has shrunk 3.75% in that direction.
How much extra fabric should I buy for shrinkage?
Divide the length you need by (1 − shrinkage). For 3 yards of washed fabric at 4% shrinkage you need 3 ÷ 0.96 = 3.125 yards, so buy 3⅛ yards. Many sewists also add 5–10% for straightening the grain.
How much does cotton fabric shrink?
Quilting cotton commonly shrinks about 2–5% in the first wash and dry, flannel and loosely woven cotton often more. The exact amount depends on the weave, finishing and how hot you wash and dry, so testing a swatch is the reliable way to know.
Does fabric shrink more in length or width?
Woven fabrics often shrink more along the length (the warp) because those yarns are held under more tension during weaving and finishing. Knits frequently shrink in length while getting slightly wider. Measure both directions.
Should I pre-wash fabric before sewing?
Pre-wash if the finished item will be washed and you want it to keep its size, if you are mixing fabrics that may shrink differently, or if dyes might run. Many quilters skip pre-washing on purpose to get a crinkled look after the first wash.
What is sanforized fabric?
Sanforizing is a mechanical pre-shrinking process used on cotton, especially denim and shirting. It limits residual shrinkage to a small amount, typically around 1–3%, compared with much more for raw, unsanforized denim.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.