Why does a garment come back a different size after washing?
Washing can shrink, stretch or twist fabric; checking the cloth, wash conditions and agreed measurement limits explains whether the change is acceptable.
Quick answers from this guide
Why can clothes change size after washing?
Clothes can change size because fabric can shrink or grow when washed. Knitted fabric can also twist, pulling a side seam towards the front. The result depends on the cloth and the washing conditions. A useful test measures change along the fabric's length and across its width, with a separate check for twisting where needed.
What should a fabric wash test report tell the brand?
A fabric wash test report should give the change in length and width alongside the washing method, temperature and number of washes. The report must identify the batch and colour tested so the result can be matched to the cloth being used. The brand then compares those measurements with the limits agreed with the maker.
How much shrinkage is acceptable?
Acceptable shrinkage is set by the brand's written requirements for the clothes. A laboratory measures the change, and that result is checked against the agreed limit under the agreed washing conditions. A report marked as passing against the fabric maker's own limits may still fall outside the limits the brand has set.
Does an approved fabric sample cover the cloth used to make the clothes?
An approved fabric sample shows what that piece of cloth can do. Yarn and dye batches can vary, and a treatment applied to a sample length can behave differently when applied during a larger run. The cloth being used for the clothes needs its own test evidence, matched to the delivered batch before cutting begins.
On this page 5 sections
A garment can come back a different size after washing because its fabric shrinks or grows under the wash conditions used; knitted fabric can also twist and change its shape. The useful answer for the brand comes from measuring that change under stated conditions and checking it against what was agreed with the maker.
Looking at the unwashed clothes cannot settle this. A piece of fabric can look right hanging up, and a finished garment can have the agreed measurements, without showing what will happen in a wash. That needs a test.
01Length, width and twisting need separate checks
A wash test reports change along the fabric's length and across its width. Keep those results separate when reading the report. A single statement that the fabric has passed a shrinkage test leaves out the measurements needed to judge whether it meets the requirements for the clothes.
Shrinkage is only part of the check. Fabric can grow as well, so ask for the measured change in both directions. The written requirements should say what change is acceptable, giving the maker and the laboratory a clear basis for checking the result. Calling the test a shrinkage test should not hide a result showing growth.
For knitted clothes, ask about twisting too. This is the movement that can pull a T-shirt's side seam round towards the front after washing. A fabric that looks fine laid flat can still twist in the wash. The report should give a separate result for this movement, checked against an agreed limit.
Together, these checks describe different ways the clothes can change. Passing a length and width check does not settle whether a knitted garment will keep its side seams where they belong.
02A wash result needs its washing conditions beside it
The same fabric can give different results under different washing conditions. Temperature matters, as does the number of washes. The washing programme belongs beside the measurements, because a result without that information does not describe a test that the brand can judge properly.
When a maker sends a report, read how the fabric was washed before accepting the result. Ask for the washing method and temperature, then check how many washes the fabric went through. If that information is missing, ask the maker or laboratory to supply it with the report.
This also matters when comparing fabrics. A result from a gentler wash cannot be treated as equivalent to one from a harsher wash. Before using reports to choose between cloths, check whether their methods and conditions allow the results to be compared. Otherwise, the apparent difference may come from the tests themselves.
Keep the conditions with the result wherever approval is recorded.
03The brand's written limits decide whether the result passes
There is no single acceptable shrinkage figure for every kind of clothing. The result is read against the limits written for the clothes being made. Agree those limits with the maker before the main fabric order moves into production, and put them in the document that tells the maker what to make.
That document should connect each acceptable measurement change to the washing conditions used to check it. For knitted fabric, include the limit for twisting where that check is needed. The measurements and the method belong together throughout approval.
A laboratory measures what happens to the fabric. Whether the result passes comes from the requirements it is being checked against. This distinction matters when a report arrives with a prominent pass mark: the fabric maker may have used its own internal limits.
Read the measured results against the brand's agreed limits even when the report says the fabric passed. If the report does not show which limits were used, ask for them. Approval needs to answer whether this cloth meets the agreement for these clothes under the stated wash conditions.
04An approved sample does not prove the delivered cloth will behave the same way
The sample establishes what one piece of fabric can do. The cloth delivered for the full order is a separate check. Yarn deliveries and dye batches vary. A treatment applied by hand to a sample length can behave differently when applied continuously during production.
Match the report to the fabric that will be cut. Check the batch number and colour, along with the fabric description and report date. Evidence from an earlier batch or a neighbouring shade does not establish how the delivered cloth will behave.
Before approving cutting, ask the maker to connect the test result to the cloth being approved.
For a long order, fabric may arrive in several batches or over a period of weeks. A satisfactory result at the start does not cover every later delivery. Arrange checks during production where later batches need their own evidence.
05Test before cutting, when a fabric problem is cheaper to address
Fabric approval is the main point to test for size change. Once faulty cloth has been cut and sewn, the work and added materials are already part of the cost of the problem. Checking before cutting keeps the decision at the fabric stage.
A visual check of finished clothes cannot replace washing evidence. It can reveal visible faults such as a broken stitch, but it cannot show how much the fabric will shrink in a customer's wash.
The maker's own laboratory can provide useful results. When using a new maker, or when a result sits close to the agreed limit, an accredited independent laboratory provides evidence from outside the organisation supplying the fabric. Ask for the report early enough to use it in the approval decision.
Keep the matching fabric details, complete wash results and agreed limits together. That gives the brand a clear record of what was tested and why it was accepted before the cloth became clothes.