Fabric formula
Percentage change in a measured distance after washing or another treatment. Negative values mean shrinkage and positive values mean growth.
Dimensional change % = (after - before) / before × 100
| Symbol | Meaning | Unit |
|---|---|---|
| L_b | Benchmark distance before treatment | cm |
| L_a | Benchmark distance after treatment | cm |
Use it for fabric and garment wash tests, in length and width separately, and to decide pattern compensation.
Benchmarks 50.0 cm apart measure 48.3 cm after washing in the length direction and 49.1 cm in the width direction.
To finish at 70 cm after 3.4% shrinkage, cut at 70 / (1 - 0.034) = 72.5 cm.
Why woven and knitted fabrics shrink, how shrinkage is measured and calculated, typical causes in knitting, weaving and finishing, and how factories control shrinkage through relaxation, compaction and pattern allowance.
How a fabric shrinkage (dimensional stability) test is done: specimen size and benchmarks, conditioning, wash and dry procedures, the shrinkage formula with worked examples, in-house checks versus lab tests, and how to read and act on the report.