Fabric Shrinkage Calculator

How to use the fabric shrinkage calculator

1. Measure one marked span before treatment, then measure that same span afterward. Use the same direction and consistent measuring conditions; do not compare one piece's width with another piece's length.
2. Choose centimeters or inches and enter the before and after measurements. The result identifies shrinkage, growth or no measured change. Run a separate calculation if you also need the other direction.
3. For a project estimate, enable Estimate size before washing and enter the size you want afterward. Read the assumption beside the estimate and check your own sample before cutting. Copy or print the current qualified result if useful.

What this tool does

• Calculates one measured direction from just two sizes, without requiring fabric composition, temperature or both length and width.
• Names shrinkage and growth clearly, including small changes that would otherwise appear to be zero after rounding.
• Optionally estimates a starting size from the original before-and-after ratio, not from the rounded percentage on screen.
• Keeps physical measurements through centimeter/inch switches and offers a qualified text summary to copy or print.

When it is useful

• Checking a washable sewing sample before planning a dimension for a garment, quilt or other fabric project.
• Describing how one garment measurement changed after care, without assuming that every part changed by the same percentage.
• Comparing your own measured before-and-after spans under a defined treatment; this arithmetic is not a laboratory test report.

Understanding fabric shrinkage and growth

For shrinkage, subtract the after measurement from the before measurement, divide by the before measurement and multiply by 100. Growth uses the increase relative to that same original measurement. The tool uses a positive magnitude and a clear direction label rather than showing growth as negative shrinkage.

Width and length are separate observations. Do not average their percentages or add them to claim an area change. Compare the same marked points in the same direction, and keep measuring conditions consistent. Follow the fabric or garment's care instructions; this calculator does not choose a wash or drying treatment.

Percentages are rounded to one decimal. A nonzero change below 0.1% is shown as less than 0.1%; shrinkage above 99.9% is described as more than 99.9% rather than an apparent 100%. These are display rules, not statements about measurement accuracy or fabric quality.

The optional starting size equals desired after size × before measurement ÷ after measurement. It assumes the same proportional change repeats in the same direction. It does not simply add the shrinkage percentage, predict a future wash or include seam, hem, layout or buying allowances.

Worked examples

A span changes from 100 cm to 95 cm: it shrank by 5%. For a desired 100 cm after washing, the repeated-ratio estimate is 100 × 100 ÷ 95, or about 105.26 cm before washing. This is an estimate to check, not a guaranteed cutting size.

A span changes from 100 cm to 105 cm: it grew by 5%. The same mathematical model estimates about 95.24 cm before treatment for a desired 100 cm afterward. Observed growth does not prove that stretching is permanent or will repeat.

A 3 cm span becomes 2 cm. The displayed shrinkage is 33.3%, but a desired 100 cm uses the original ratio: 100 × 3 ÷ 2 = 150 cm. Using the rounded percentage instead would give a different estimate. A separate inch example, 10 in becoming 9.5 in, shows 5% shrinkage.

What the result cannot tell you

The percentage describes your entered measurements, not every part of a garment, material quality, an acceptable tolerance or later wash behavior. Fiber, construction, finish, treatment and measuring conditions can matter; no preset shrinkage rate is assumed.

This calculator does not perform an AATCC or ISO test, certify dimensional stability, choose a care treatment or guarantee fit. If a buyer or laboratory requires a defined procedure, follow that procedure and specification separately. Product-specific care instructions take priority.

The optional estimate is for one dimension and assumes repeatable proportional change. It is not fabric yardage, a pattern layout or a shopping list. Values are rounded for readability; tiny estimates stay explicitly positive. Very large mathematical estimates should be rechecked rather than treated as practical cutting recommendations.

Measurements and privacy

The calculation runs in your browser. This tool does not save your entered measurements, upload them for calculation or put them into shareable URLs. Normal site features and consent choices still apply.

Copy and print include only the current valid measurements, result and its qualifications. Review the summary before sharing it. An already-completed clipboard write or started print job cannot be recalled by clearing the page.