Grading Rules Explained: How Pattern Sizes Actually Scale
A single pattern only fits one body. Grading is how that one pattern becomes an XS, a size 12, and everything in between, without redrawing the design from scratch for each size. Get the rules wrong, and your size run stops fitting the way your sample did, no matter how good that original sample was.
This guide breaks down how grading actually works, the increments manufacturers use, and the mistakes that turn a clean size chart into a returns problem.
What Is Grading?
Grading is the process of scaling a base pattern up or down to create a full size range. A pattern maker builds one master pattern, usually in a middle size like M, then applies fixed measurement increases or decreases at specific points to generate every other size.
Those fixed amounts are called grade rules. A grade rule might add 2 centimeters to the chest at every size up, while adding only 1 centimeter to the shoulder. Different points on the body grow at different rates, so a flat, uniform scale-up rarely works.
This is also where a tech pack earns its place in the process. The point of measure chart in a tech pack is where grade rules actually get written down and sent to the factory, so grading and tech packs are really two halves of the same job.
How Grade Rules Work
Every point of measure on a garment gets its own grade rule. Chest, waist, hip, shoulder width, sleeve length, and body length each increase by a different amount between sizes, based on how real bodies change shape as they get bigger.
A typical adult unisex hoodie might use something close to this between adjacent sizes:
- Chest width: +4 cm per size
- Body length: +2 cm per size
- Sleeve length: +1.5 cm per size
- Shoulder width: +1 cm per size
These numbers are not universal. A fitted dress shirt grades differently from an oversized hoodie, and a children’s line grades differently again from adult sizing. Grade rules should always be based on your own fit sessions, not copied from a generic chart.
Grading Methods
Manual Grading
Manual grading uses a ruler and the original pattern pieces, shifting cut lines outward or inward by the grade rule amount at each point. It is slow and requires real pattern-making skill, but it gives a pattern maker full control over how each size behaves, which matters for brands with an unusual fit or silhouette.
CAD Grading
Most manufacturers now grade digitally, using pattern software such as Gerber, Lectra, or Optitex. The pattern maker inputs the grade rules once, and the software generates every size automatically. This is faster and more consistent across a size run, and it is what almost every overseas factory will expect to receive.
If you are working with a full inventory manufacturer rather than a small sample maker, they will typically handle CAD grading in-house once you approve the base pattern and grade rules.
Common Grading Mistakes
Most sizing complaints trace back to one of a handful of grading errors, not to the base pattern itself.
- Flat grading: applying the same increase to every measurement point, which distorts proportions at the largest and smallest sizes.
- No fit testing across the range: approving a sample in one size only, then assuming the graded sizes will fit the same way.
- Ignoring fabric behavior: a grade rule that works for a woven cotton will not necessarily work for a stretch jersey, since stretch fabrics need smaller increments.
- Ambiguous tolerances: not specifying how much a finished measurement is allowed to vary from the spec, which gives the factory room to drift between sizes.
A clear size chart for the customer-facing side helps, but it only reflects what the grading actually produced. If the grade rules are wrong, a nicely formatted size chart just documents the wrong numbers more clearly.
Getting Grading Right As a Small Brand
You do not need to learn CAD grading software to launch a brand with correctly sized garments. What matters is asking your pattern maker or manufacturer the right questions before production starts.
- Ask which grade rules they plan to use, and request the point of measure chart in writing, not just a verbal description.
- Request a graded sample in at least one size beyond your base sample, usually the smallest or largest in your range, before approving bulk production.
- According to industry sizing standards published by ASTM International, tolerances of a few millimeters are normal at each point of measure, so build that expectation into your quality control rather than treating every deviation as a factory error.
Once your grade rules are confirmed, they belong in your tech pack’s point of measure chart with tolerances listed for every size, not just described in an email thread that gets lost between sample rounds.
Frequently Asked Questions about Grading
A grade rule is the fixed amount a specific measurement point, such as chest width or sleeve length, increases or decreases between adjacent sizes. Each point of measure on a garment typically has its own grade rule.
No. Grade rules depend on the garment type, fit, and fabric. An oversized hoodie, a fitted dress shirt, and a stretch legging all use different increments between sizes, even if they share a similar size range like XS to XL.
Yes, manual grading with a ruler and the base pattern is possible and is still how many independent pattern makers work. It takes more time and skill than CAD grading, but it gives full control over how each size behaves.
Most small brands start with a core range such as XS to XL or S to XXL. Adding more sizes later is easier once your grade rules are proven to fit correctly across your existing range.
