How to grade knit patterns for T-shirts and hoodies

Grading is the process of turning the base-size pattern into patterns for every other size. It looks like a technical job, usually done in software, but the decisions behind it are commercial: who the end customer is, how loose the garment should be, how the extreme sizes look. Poor grading produces complaints that the size M sample never warned you about.

Base size and size range

The first step is choosing the base size, the one the sample is made and approved in. It is usually M for adult collections, or a size in the middle of the range for kidswear. Fit sessions are done on it, and after approval it is graded up and down.

Agree the size range clearly with the client: XS–XL, S–XXL, S–3XL? Each size added at either end raises the risk, because grading deviations accumulate. A 3XL graded linearly from M can come out out of proportion if you do not adjust the rules.

Grade rules per point of measure

Grading works on the same points of measure as the measurement chart. For each point you set the increment between two consecutive sizes. As a rough guide for a basic unisex tee, many producers use increments in the region of:

• chest width: 2–3 cm per size (so 4–6 cm on the circumference);
• body length: 1.5–2 cm per size;
• shoulder width: 1–1.5 cm per size;
• short sleeve length: 0.5–1 cm per size;
• neck width: 0.5–1 cm per size;
• front neck drop: 0.3–0.5 cm per size.

The values depend on the brand, the market and the cut. An oversized brand may grade width in larger steps and length in smaller ones. What matters is that the increments are documented and approved by the client before production.

Linear and non-linear grading

In linear grading the increment is the same between all sizes. It is simple and works well for short runs of four or five sizes. For long ranges, many pattern makers use non-linear grading: increments grow towards the larger sizes, especially for widths, because body proportions do not grow evenly.

Hoodies add a few specific points:

• the hood is graded moderately, because head size varies less than body size;
• the kangaroo pocket grows with the front, but its position is referenced from the shoulder;
• rib cuffs and waistband are graded to the opening they are sewn into, keeping the same stretch ratio.

Checking the graded run

Never go straight from grading to bulk. The right steps are:

1. Check the graded patterns in the software: seams that join must have the same length in every size.
2. Sew a size set, one piece of each size, in production fabric.
3. Measure every piece at every point and compare with the chart.
4. Fit at least the smallest and largest sizes on real people.
5. Send the results to the client and ask for written approval.

A size set costs little compared with an order in which every XL comes out too short.

Fabric matters in grading too

Grading assumes the fabric behaves the same in every size. So cut the size set from the same lot as production, and build shrinkage into every pattern, not just the base size. On light fabrics, such as a summer tee, twist and widthwise shrinkage can affect larger sizes more.

A practical example: for a soft-handle summer tee, a fabric such as our anthracite melange 155 g single jersey works well, and the melange colour hides small shade differences between lots. Because it is a light jersey, test shrinkage on a sample piece and include the correction in every graded pattern.

Who does the grading

Grading may be done by the workshop's pattern maker, an outside pattern bureau or the client. Whoever does it, the producing workshop must receive the final patterns in a clear format, with file name, size and revision. When the client sends graded patterns, check them with a size set before you accept responsibility for the measurements.

For size sets and samples you can buy fabric from our current stock, by the roll with no minimum, and order the same quality for production. If you need another shade, ask for a made-to-order quote, from 150 kg per colour.