How much shrinkage should I accept on cotton briefs in bulk production?

Short answer: There is no single universal shrinkage figure for cotton briefs. The acceptable limit should be agreed between buyer and factory for the specific fabric, based on a named test method and washing procedure, and written into the purchase specification for length and width separately. What matters is that the limit is defined, tested on bulk fabric and reflected in the size chart.

Why cotton knit changes size

Cotton jersey and rib are stretched during knitting, dyeing and finishing. When the garment is washed and dried, part of that stretch relaxes and the fabric returns toward a more stable state, which shows up as shrinkage, usually more in length than width for a knit. Compaction and pre-shrinking finishes reduce this, but the amount varies by fabric and process.

What to agree

• Method: ISO 5077 describes how to determine dimensional change after washing and drying, with the wash and dry procedure taken from ISO 6330. Results are reported as a percentage for length and width, with a minus sign for shrinkage.
• Procedure: choose the wash temperature and drying method that matches your care label. A tumble-dry result and a line-dry result are not interchangeable.
• Number of cycles: one wash or several — state it.
• Tolerance: agree a figure for length and width for that fabric; your lab or the factory’s historical data for the same quality is the basis, not a number from another product.

How to apply it in bulk

• Test the bulk fabric before cutting, not just the sample fabric.
• Ask whether the pattern already allows for the measured shrinkage. Patterns can be graded to compensate, but only if the result is known before cutting.
• Re-check finished garments after washing at final inspection, measuring key points such as waist, leg opening and rise.

Risk limits

Elastic waistbands and leg bands behave differently from the body fabric, so a body-fabric result does not cover the whole garment. Garment-dyed products follow a different sequence and need measurements after dyeing. If a care-related promise such as "pre-shrunk" is used in marketing, keep the test report that supports it.

Facts, recommendations and uncertainty

Established: knitted cotton relaxes when washed and the change can be measured. Recommendation: agree method, procedure and tolerance per fabric. Uncertain: any figure quoted without the test conditions behind it.

Sources and further reading

• ISO 5077:2007 — Determination of dimensional change in washing and drying
• ISO 6330:2021 — Domestic washing and drying procedures for textile testing
• U.S. FTC — Care Labeling Rule (16 CFR Part 423)

Standards and regulations are referenced by their published scope. Test parameters, cycles and pass levels should be agreed with your laboratory for the specific product; legal requirements should be confirmed for each destination market.