Two documents, one system
Buyers often treat the size chart and the grade rules as one thing. They are related but serve different readers. The customer-facing size chart tells a shopper which size to choose, usually from body measurements. The grade rules, inside the tech pack, tell the pattern maker how each garment measurement changes from one size to the next. If the two are built separately, the chart promises one fit and the garments deliver another.
A good process builds the grade rules first, confirms them on physical samples, and then writes the customer chart from the confirmed garments. This note explains that sequence without prescribing grade values, because the right values depend on your customer, your fabric and your fit.
Step one: choose the base size and fit it
Every pattern starts in one size, called the base or sample size. Choose a size near the middle of your range, because grading outward in both directions keeps errors smaller at the extremes. Fit the base sample on a fit model whose body measurements match your intended base size, and correct it through as many rounds as needed. Do not grade an unapproved base: every error in the base is multiplied across the range.
The typical reference window for a first sample is 7-15 days, confirmed in writing for each program. Plan for more than one fit round on new blocks.
Step two: define points of measure
Points of measure are the garment measurements that are graded and inspected. Each needs a name, a written method and a tolerance. For leggings, typical points include waist relaxed, waist extended, front rise, back rise, hip, thigh, knee, leg opening and inseam. For bras, they include underband relaxed and extended, band width, front length, strap length and armhole. The method matters: a hip measured at a fixed distance below the waist and a hip measured at the widest point are different numbers.
| Column | Content | Who sets it |
|---|---|---|
| Point of measure | Name and written method, with a drawing reference | Buyer with pattern maker |
| Base size value | Measurement on the approved base sample | Confirmed on sample |
| Grade per size step | How much the point changes between neighboring sizes | Pattern maker proposes; buyer confirms |
| Break points | Where the grade changes, for example at extended sizes | Pattern maker proposes; confirmed on size set |
| Tolerance | Allowed difference at inspection | Buyer sets on tech pack |
Step three: build the grade rules
Grade rules describe how each point of measure changes between neighboring sizes. They are not universal. A brand dressing a studio customer, a brand with an extended size range and a brand with a compressive fit will each grade differently. The pattern maker usually proposes grade rules from their block and experience, and you check them against your target customer's body measurements and your fit intent.
Several decisions shape the rules:
- Which points grade and which stay constant. Inseam, for example, may stay the same across sizes or grade slightly. Waistband height may be fixed. Write each choice.
- Even or uneven steps. Grades are often even through the core range and change at break points, typically where the range extends into larger sizes, because body shape does not change in straight lines.
- Proportion between points. Waist and hip may grade at different rates. Rise often grades less than width. These proportions decide whether larger sizes look like the base or like a stretched copy.
- Fabric stretch. A highly compressive fabric and a softer fabric may need different negative ease, so grade rules tied to one fabric may not transfer to another.
Step four: confirm on a size set
Once grade rules are agreed, ask for a size set: one garment in each size, or at least the smallest, the base and the largest. Measure every point of measure on each size and compare with the graded specification. Then fit the extremes on real bodies. Problems at the ends of the range, such as a waist that is fine in the base but too tight in the largest size, show up here and are fixed by adjusting the rules, not by patching one size.
This step matters most for plus-size yoga wear, where body proportions change and break points are needed. The plus-size fit note covers that in more depth.
Step five: set tolerances
Every point of measure needs a tolerance, written on the tech pack, that inspection uses to pass or fail garments. Tolerances should reflect the fabric: stretch knits move more than wovens, so tolerances are usually wider on stretch points than on fixed points such as a woven label position. Set them before bulk, and use the same values in the inspection brief. The AQL inspection note explains how measurements are sampled at inspection.
Step six: write the customer size chart
Customer charts usually give body measurements, such as waist, hip and bust, for each size. Derive these from your fit intent and the confirmed garments, not from the garment measurements directly, because a stretch legging is smaller than the body it fits. Some brands also publish garment measurements such as inseam, which helps customers compare lengths. If you publish garment measurements, make sure they match the graded specification after laundering. Dimensional change after laundering, tested to AATCC 135, tells you whether to adjust.
Keep size names consistent across garments. If a medium legging and a medium bra fit different bodies, customers lose trust in the chart. Sets in particular need aligned sizing; see yoga sets.
Size range and MOQ
More sizes mean more grading work and a thinner split of the order. Sizes can usually be mixed within the MOQ, so a wide range does not necessarily raise the minimum, but very small quantities per size can make reorders harder to plan. As typical reference ranges, cut and sew MOQ sits around 100-300 pcs per style per color and seamless around 300-500, confirmed in writing for each program.
Seamless garments add a twist: sizes are set in the knit program, and some seamless styles cover a wide body range per size because of high stretch. Confirm how many sizes the partner factory programs for a seamless style before writing your chart.
Keeping it consistent over time
Once a block is approved and graded, keep it as the base for future styles. Reusing a confirmed block keeps sizing consistent across the line and across seasons, which reduces returns. Record the grade rules, the tolerances and the approved size set measurements in one place, and refer every new style back to them. When you are ready, send your current chart and fit notes and the desk will review them with the partner factory's pattern maker.