Garment Grading Explained: How AI Handles Size Scaling
Understand garment grading and size scaling — what grade rules are, how AI calculates graded measurements, and how to ensure accurate sizing across your size range.
What is garment grading
Garment grading is the process of scaling a base-size pattern and its measurements up and down to create a full size range. If your base size is M, grading calculates the corresponding measurements for XS, S, L, XL, and XXL.
Grading is not simply adding the same increment to every measurement. Different body points grade at different rates — chest width may increase by 2 inches per size while neck width increases by only 0.5 inches. The relationship between these increments determines how the garment fits across the size range.
Grade rules and how they work
Grade rules define the measurement increment between sizes for each point of measure. They vary by garment type, fit family, and target market. A slim-fit men's t-shirt uses different grade rules than an oversized women's hoodie.
Standard US grading typically uses 1.5-2 inch increments for chest/bust width and 1-1.5 inches for body length per size. European grading may use different increments. Grade rules also vary by brand — some brands use smaller increments for a more consistent fit across sizes.
Example grade rules: men's regular fit t-shirt
| Point of Measure | XS | S | M (base) | L | XL | XXL |
|---|---|---|---|---|---|---|
| Chest width (1/2) | 18" | 19.5" | 21" | 22.5" | 24" | 25.5" |
| Body length (HPS) | 26" | 27" | 28" | 29" | 30" | 31" |
| Shoulder width | 16" | 17" | 18" | 19" | 20" | 21" |
| Sleeve length | 7.5" | 8" | 8.5" | 9" | 9.5" | 10" |
How AI generates graded size charts
AI tech pack generators apply category-appropriate grade rules based on your garment type, fit family, and target market. When you specify a boxy oversized hoodie in size M, the AI knows to use wider grade increments than a fitted performance top.
The AI selects base measurements appropriate for your specified fit, then applies standard grade increments for each point of measure. The result is a complete graded size chart that maintains proportional accuracy across the size range.
Common grading mistakes
The most common grading mistake is using the same increment for all measurements. If chest and sleeve length grade at the same rate, larger sizes end up with sleeves that are proportionally too short. Each POM needs its own grade increment.
Another common mistake is not adjusting grade rules for fit family. Oversized garments need larger increments to maintain the oversized look across sizes — using slim-fit grade rules on an oversized garment makes the smaller sizes look oversized but the larger sizes look regular fit.
Verifying AI-generated grading
After AI generation, verify your graded size chart by checking a few key relationships: does the chest-to-waist ratio stay consistent across sizes? Does the sleeve length increase proportionally to shoulder width? Does the body length increment make sense for your garment type?
If you have an existing size chart from a previous season, compare the AI-generated chart against your proven measurements. Use the AI chat to adjust any specific grade increments that do not match your brand's fit standards.