A size chart looks simple. A table, a few numbers, a set of sizes from XS to XL. In production, however, that table becomes a contract. If it is vague, the factory must guess. If it is inconsistent, grading will multiply the error across every size. If it is approved late, fit problems are discovered only after bulk cutting.
This guide is written for buyers, merchandisers, and product developers who need a size chart that a factory can actually follow. It distinguishes three different documents that are often confused, explains what each one must contain, and gives a practical approval checklist.
1. Three documents, not one
Buyers often use the phrase size chart for three different things. Keeping them separate prevents most fit disputes.
First, the body measurement chart describes the body that the garment is designed to fit. It lists body dimensions such as chest, waist, hip, height, and inside leg length for each size. Standards work in this area, including the ISO 8559 series on size designation of clothes, is organised around body dimensions and how they are used to designate sizes. A body chart answers the question: who is this size for?
Second, the garment measurement chart, often called the spec sheet or POM (points of measurement) chart, describes the finished garment itself. It lists measurements such as chest width, body length, shoulder width, sleeve length, and waist width for each size, measured flat or on a form, using a stated method. This is the document a factory cuts and checks against.
Third, the grade rule describes how measurements change from one size to the next. For example, chest width might increase by 2 cm per size, while body length increases by 1 cm. Grading is not simply adding the same amount everywhere. Different points grade at different rates, and some points, such as neck width, may grade very little or not at all.
A buyer who sends only a body chart has not given the factory a garment specification. A buyer who sends only a garment chart, without stating how it was measured, has not given the factory a repeatable check.
2. What a garment measurement chart must contain
A usable garment measurement chart should state, at minimum:
- The garment style, sample size, and date of the chart, so later revisions do not get mixed up.
- Every point of measurement, with a clear name and a diagram or written description of exactly where it is taken.
- The measurement method: flat, on a form, stretched or relaxed, and whether seams, hems, and trims are included.
- The unit, consistently centimetres or inches, with no mixed units in the same chart.
- The value for every size in the range, not only the sample size and an instruction to grade.
- The tolerance for each point, because no production run will hit every number exactly.
Tolerances deserve special attention. A tolerance of plus or minus 1 cm on chest width is a different product decision from plus or minus 0.5 cm, especially on a fitted garment. Tolerances should be set point by point, not as a single blanket figure, and they should be agreed before production, not negotiated after a failed inspection. The site’s existing guidance on garment measurement tolerances is a useful companion here, because it explains why a tolerance is a decision, not an afterthought.
3. Grade rules: where size charts go wrong
Grading errors are expensive because they are systematic. If the grade rule for sleeve length is wrong by 0.5 cm per size, the error is small in the sample size and large at the extremes of the range.
Common grading problems include:
- Grading a point that should stay fixed, such as a pocket position or a button stance, by the same amount as a body dimension.
- Using a linear grade across a range where the body does not change linearly, for example between children’s sizes and adult sizes.
- Copying a grade rule from a different garment, fabric, or fit, such as applying a woven shirt grade to a stretch knit.
- Changing the sample size mid-development without reissuing the full graded chart.
Before bulk production, ask the factory to submit a graded spec for the full size range, not only the sample size. Check the smallest and largest sizes first, because that is where grading errors become visible. Also check any size that is a known risk for your market, such as a tall size or a plus size, rather than assuming the middle sizes prove the range.
4. Body measurements, fit intent, and the sample size
A size chart must also state its fit intent. Is the garment designed to be close-fitting, regular, relaxed, or oversized? The same body measurements can produce very different garments depending on ease, which is the difference between body size and garment size.
For example, a chest body measurement of 100 cm might correspond to a finished garment chest of 106 cm for a regular fit, 112 cm for a relaxed fit, or 102 cm for a close fit. If ease is not stated, the factory cannot know whether a garment that measures 108 cm is correct, too tight, or too loose.
The sample size matters for the same reason. A size chart approved on a medium sample does not automatically prove fit at the extremes. A fit sample should be checked on a body or form that represents the intended wearer, and the approval should record which size was fitted, what was changed, and whether the change affects the grade rule.
5. Size-set approval: a practical sequence
A workable approval sequence, adapted to most apparel orders, looks like this:
| Stage | What to approve | Evidence to keep |
|---|---|---|
| 1. Specification | Body chart, garment chart, grade rules, tolerances, measurement method | Dated, versioned chart |
| 2. Proto sample | Fit intent, construction, and key measurements in the sample size | Measured proto report |
| 3. Size-set sample | Graded measurements across the full range, especially extremes | Size-set measurement report |
| 4. Pre-production sample | Final fabric, trims, and production method in the sample size | Approved pre-production sample and report |
| 5. Bulk check | Random measurement checks by size, against the agreed chart and tolerances | Inspection measurement record |
If a stage is skipped, the risk does not disappear. It moves to bulk production, where it is more expensive to fix. Pre-production approval, in particular, should confirm that the size chart, fabric, and construction work together, not only that a single sample looks acceptable.
6. Communication mistakes that create fit returns
Several communication habits cause more fit problems than the numbers themselves:
- Sending a size chart as a photograph of a handwritten table, with no editable version and no version date.
- Changing one measurement by email, without reissuing the full chart, so the factory works from two conflicting versions.
- Using different names for the same point of measurement in the tech pack, the size chart, and the inspection brief.
- Approving a sample by saying it fits, without recording which measurements were checked and which were not.
- Treating a retail size label, such as M or 38, as a measurement. A label is a code. It only has meaning when it is tied to a specific body and garment chart for a specific market.
A simple discipline helps: one current chart, one version number, one owner on each side, and every change issued as a new version, not as a comment in a chat thread.
7. Buyer checklist before grading starts
Use this checklist before the factory grades or cuts bulk:
- Body chart, garment chart, and grade rules are in the same versioned document set.
- Every point of measurement is named, diagrammed, and measured by a stated method.
- Tolerances are set point by point and agreed in writing.
- Fit intent and ease are stated for the style, not assumed from a previous style.
- The full graded range, including smallest and largest sizes, will be submitted for approval.
- Size-set and pre-production approvals are scheduled before bulk cutting, with time to correct grading errors.
- Internal references are consistent: the tech pack, size chart, and inspection brief use the same points and tolerances.
A size chart is not a marketing table. It is a production specification. When it is complete, versioned, and approved in the right sequence, grading becomes a controlled step rather than a source of returns, rework, and disputes about what a size was supposed to mean.
