How much shrinkage is acceptable in sportswear and fleece?

Is there a standard shrinkage limit for sportswear?

No. ISO 5077, and AATCC TM135 for fabrics and TM150 for garments, describe how to measure dimensional change after washing and drying; none of them says how much change is acceptable. The limit is a commercial term, and it belongs in the specification next to the method.

Intertek’s published criteria for its voluntary “Durable” High-Performance Mark for activewear garments give one checkable reference point. Using ISO 6330 washing and ISO 5077 measurement, they allow ±5% for knitted T-shirts, shirts, midlayers, pants and shorts and ±3% for woven shirts, jackets, pants and shorts, and they cap spirality at 5% under ISO 16322-3 Procedure B. That is one scheme’s line, not a regulation, and a tighter limit may be needed where the size chart leaves little room.

Why do knitted garments change size in the wash?

Knitted fabric is made and finished under tension, and washing releases it. Knits often shrink in length while growing slightly in width, so measure both directions.

Cotton fleece and French terry usually move more than heat-set polyester knits, and elastane blends depend heavily on correct heat-setting. Garment-washed or pre-washed styles have less shrinkage left in them, but the pattern must allow for the shrinkage taken out during that wash. The table separates four mechanisms, because each has a different fix.

How should shrinkage be tested?

Mark fixed points, wash and dry with named procedures, re-measure, and report the change at each point. ISO 3759 covers preparing, marking and measuring specimens and garments; ISO 6330 supplies the washing and drying procedures; ISO 5077 combines them and expresses dimensional change as (after − before) ÷ before × 100, with a minus sign for shrinkage and a plus sign for extension.

ISO 6330:2021 contains 16 washing procedures for its front-loading reference machine, further procedures for two top-loading types, and six drying procedures from line drying to tumble drying. A requirement therefore needs both codes, for example procedure 4N (40 °C, normal programme) with drying procedure F (tumble dry), not just “40 °C wash”.

• Washing and drying procedure codes and the number of cycles; many buyers check after 1 cycle and again after 3 or 5.
• Measuring points, marked so the same line is measured before and after.
• Conditioning before each measurement, so moisture does not distort the reading.
• Garments per size and colour, with each garment reported, not only the average.
• A limit for each point, plus a separate spirality limit.

How do you set a limit that fits the size chart?

Convert the percentage into centimetres and compare it with the garment tolerance; the table below uses hypothetical size L measurements.

SenLin’s published garment tolerance is 1–2 cm for performance tops, shorts, pants and sets and 1–3 cm for hoodies, sweatpants and fleece sets; any shrinkage test and limit is agreed per order, and SenLin publishes no in-house laboratory results. A 3% change on a 74 cm body length removes 2.2 cm, more than even the 2 cm end of that range, so fit cannot rely on shrinkage staying “within tolerance”. Either the fabric is stabilised until residual shrinkage is small against the tolerance, or the pattern is cut larger by an allowance taken from a test on the bulk fabric lot.

Write down whether the size chart describes the garment as shipped or after the first wash. Without that sentence, a factory measuring new goods and a customer measuring washed ones can both be right.

Which garment points should be measured?

Measure the points that drive fit and complaints, on every size you test.

• Tops: body length from the high point shoulder, half chest below the armhole, hem width, sleeve length and cuff opening.
• Polos: collar length and placket, where fabric and interlining can shrink at different rates.
• Shorts and pants: relaxed waist, hip, inside leg and leg opening.
• Hoodies and sweatpants: hood height and the width of rib cuffs and waistbands, since rib and body fabric behave differently.
• Twist: side-seam displacement on tees and leggings, measured with ISO 16322-3 or AATCC TM207.
• Decorated areas: a heat transfer, reflective print or dense embroidery may not move with the fabric, so check for puckering or cracking around it.

How does shrinkage testing connect to the care label?

Test the care instruction you intend to print. Under the US FTC Care Labeling Rule, care instructions need a reasonable basis, such as reliable test results, and the label must warn about any part of the washing procedure consumers can reasonably be expected to use that would harm the product. If the label says tumble dry low, a line-dry test does not support it; if line drying is what keeps the garment within its limit, say so on the label.

Agree the measuring points, procedures and limits before sampling, so that the approved sample, the bulk check and the printed care label all refer to the same test. Changing the care instruction after approval means testing again.