Oct 30, 2026
How to Control Fabric Shrinkage in Activewear
A legging that measures perfectly in the sample room and arrives shorter after one wash is not a sewing failure. It is an untested fabric decision.
A legging that measures perfectly in the sample room and arrives two centimetres shorter after the first wash is not a sewing failure. It is a fabric decision that was never tested. Shrinkage is one of the few defects that affects every piece in the order at once, which makes it the most expensive kind of surprise.
This is how shrinkage happens, what the standards actually measure, and what a buyer can specify so the garment still fits after ten washes.
Where shrinkage comes from
Knitted fabric is under tension from the moment it leaves the machine. Yarn is stretched during knitting, stretched again during dyeing, and held in that state until it is dried and set. The fabric only finds its natural dimensions when it is relaxed, and the first wash is the most thorough relaxation it will ever receive.
Knitting tension. Fabric knitted tightly and then relaxed will contract more than fabric knitted loosely. A mill that runs tight to save width will produce fabric that shrinks on the first wash.
Dyeing and finishing. Heat setting fixes dimensions. Compaction, a process that deliberately shrinks fabric under controlled conditions, is used to make the final dimensions stable. Mills that skip or shorten compaction sell fabric that is cheaper per metre and more expensive per garment.
Elastane content. Higher elastane means more recovery force pulling the fabric back to a shorter state. A 20 percent elastane fabric will move more than a 5 percent one unless it is properly set.
Garment construction. A seam sewn under tension can shrink the panel around it. This is why the same fabric can produce leggings that shrink differently depending on who sewed them.
What the standards measure
Dimensional change after washing is the property that matters, and it is measured on a marked square of fabric or on a finished garment, before and after a defined wash cycle.
Typical buyer limits sit around 5 percent lengthwise and 5 percent widthwise for knit activewear, with tighter limits on premium programmes. The number only means something alongside the wash standard, the temperature and the drying method, because tumble drying can double the shrinkage of a fabric that passes a line-dry test.
Ask for both numbers: shrinkage after line drying and shrinkage after tumble drying. Many customers tumble dry, and a programme approved only on line drying will generate returns.
Why samples hide the problem
Sample garments are often made from fabric that has already been handled, pressed and re-cut. Pressing relaxes the fabric, so the sample measures correctly. Bulk fabric arrives from the mill in a different state, is cut in fewer passes, and reaches the customer without that extra relaxation.
The result is a bulk order that measures 2 to 3 percent shorter than the approved sample, and a fit complaint that the factory cannot reproduce on the sample.
How to control it
Step 1. Ask for the fabric's shrinkage figure with the test method. Not a range, a number, with the standard and the drying method.
Step 2. Wash the bulk fabric before cutting, or buy pre-shrunk fabric. This is the only reliable fix, and it costs fabric width.
Step 3. Cut with a shrinkage allowance if you cannot pre-wash. Add the expected percentage to the pattern in the direction the fabric shrinks, not uniformly.
Step 4. Sew at consistent tension. A seam sewn tight will pull the panel in, and no cutting allowance will correct it.
Step 5. Test the finished garment, not just the fabric. Seams, waistbands and hems change the behaviour.
Step 6. Record the result and keep a retained sample. The next lot is compared against that, not against memory.
What to write in the tech pack
Maximum shrinkage lengthwise and widthwise, as a percentage, with the wash standard named.
Drying method used for the test, and whether tumble drying is covered.
Measurement points and how they are measured, because a waistband measured relaxed and a waistband measured stretched give different answers.
Tolerance on each key measurement, typically plus or minus 5 mm on a waistband and plus or minus 10 mm on an inseam.
Pre-shrunk requirement, if the fabric must be washed before cutting. State it, because it changes the fabric order quantity and the cost.
Questions buyers ask us about shrinkage
Why did only one colour shrink?
Different dye lots and different finishing runs. Colour and shrinkage are both consequences of the dyeing process, so a colour that needed extra processing can behave differently.
Can we fix shrinkage by cutting larger?
Only if the shrinkage is uniform and known. Cutting larger hides the problem for one wash and creates a garment that is too big before it is washed.
Does a heavier fabric shrink less?
Not necessarily. Weight and shrinkage are different properties. A dense, well-compacted fabric shrinks less than a light one, but a heavy fabric with poor compaction can shrink more than a light one with good compaction.
The bottom line
Shrinkage is decided at the mill and revealed at the customer's washing machine. Buyers who ask for the number, the method and the drying condition, and who test the finished garment rather than the swatch, avoid the most expensive fit complaint in the category.
If you want the shrinkage behaviour of a fabric checked before bulk, send us the spec and the intended wash instructions. Email breezsportswear@126.com or message WhatsApp +86 181 4865 3131. Breez Sportswear develops private-label activewear and tests garments after washing, not only on the table.