Clothing Sizes & Grade Rules: How Patterns Scale Across Your Size Curve
Grading is the quiet step that decides whether your size Small actually fits like a Small across every style. Get it wrong and you ship a size curve where the Medium is too tight and the Large is too loose. Here's how a single base pattern becomes a full XS–XXL run, and the rules that keep it consistent.
What Grading Actually Is
A pattern maker drafts one "base size" — usually a Medium. Grading is the mathematical process of increasing or decreasing that base pattern by fixed increments to create every other size. The factory doesn't redraw each size; it applies your grade rule to the base. That's why a clear, written grade rule is part of every proper tech pack.
Standard Grade Increments (Women's Woven, per size step)
| Measurement point | Increment per size | Notes |
|---|---|---|
| Bust | 2.5–3.8 cm | Larger at outer sizes |
| Waist | 2.5–3 cm | Follows bust closely |
| Hip | 3–3.8 cm | Stable across curve |
| Garment length | 1.3–2 cm | Dress vs top differ |
| Sleeve length | 1.3–1.9 cm | Outerwear slightly more |
These are starting points. Stretch fabrics, plus-size curves, and petite ranges each need their own rule — a one-size-fits-all grade is a common beginner mistake.
Build Your Size Curve
Most small brands launch with XS–XL (or S–XXL). Decide the spread before sampling: adding XXL later means re-grading and re-testing the top of the curve, which costs a second sample round. A typical entry curve for women's apparel:
- XS: base − 2 steps
- S / M / L: the core, with M as the graded base
- XL / XXL: +1 / +2 steps, with adjusted grade for plus fit
How Grading Works at the Factory
You provide a size spec (measurements for each size) inside the tech pack. The factory's CAD system grades the base pattern to those numbers and cuts all sizes from one marker. If your spec and the factory's default grade differ, confirm which one they'll use — mismatches are a top cause of "the sample fit but production didn't."
Common Sizing Mistakes
- No written grade rule — the factory guesses, and every reorder drifts.
- Mixing men's and women's grades on unisex items without a decision.
- Copying a competitor's size label without checking the actual measurements.
- Changing the base size mid-run — it shifts the whole curve silently.
Frequently Asked Questions
What does "grade rule" mean in clothing?
It's the set of increments used to scale a base pattern into other sizes. A written grade rule keeps every size consistent and makes reorders predictable.
Do I need different grading for stretch fabric?
Yes. Stretch garments use smaller grade increments because the fabric gives; over-grading a knit makes large sizes baggy. Your tech pack should specify stretch vs woven grading.
How many sizes should a new brand launch with?
XS–XL covers most demand for a first run and keeps sampling cost contained. Add XXL only if your audience needs it — but plan the grade now so you're not re-sampling later.
Why does my production size differ from the sample?
Usually a grade-rule mismatch: the sample was cut from the base size, but production used a different rule at the extremes. Confirm the factory applies your spec sheet exactly.