Armhole and Neckline Grading Rules Between Sizes

Armhole and neckline grading rules are not a single standard: every patternmaking school and every CAD system builds its own chart, but a common guideline deepens the armhole by 5 to 10 mm per size and widens it by 3 to 7 mm, while the neckline grows a little in width and somewhat more in drop, split differently between front and back. What is non-negotiable is keeping alignment: the armhole point and the neckline point must stay aligned with the rest of the pattern in every size.

Modeltex production guide. Updated on Sep 8, 2026.

What it means to grade the armhole and the neckline

Grading a pattern means moving each point of the outline the distance given by an increment chart, to generate the other sizes without losing the shape of the piece. The armhole and the neckline are open curves, not a closed outline like the bust or the hip: they connect the front and back to another piece (sleeve, collar or binding) and have to keep fitting that piece in every size.

That is why they are graded with their own logic, separate from the bust girth: you have to decide how far each point moves (the highest point, the side point, the base of the neckline) so the shape holds and the piece sewn to it still fits.

How much the armhole deepens and widens per size

There is no official figure: each school, each CAD system and each manufacturer builds its own chart, and the number changes with the type of garment (a t-shirt does not grade the same as a fitted blazer). As a guide:

Armhole depth (from the shoulder down): 5 to 10 mm more per size.
Armhole width (how much it opens between front and back at the armhole point): 3 to 7 mm per size.
In the extreme sizes (3XL, 4XL) both increments usually accelerate, just like the bust girth.

How the neckline growth is split between width and drop

The neckline grows in two directions that are handled separately: the width (the distance between the two shoulder points) and the drop, which is how far the neckline goes down on the chest or the back. A style may need more width and little drop, or the reverse, depending on the design of the garment.

Neckline width: 3 to 5 mm per size, tied to the growth of the shoulder width.
Front neckline drop: 3 to 6 mm per size.
Back neckline drop: 1 to 3 mm per size, because the back has less volume to accommodate than the front.

Why the armhole does not grow like the bust girth

The bust or chest girth usually grows 4 to 6 cm per size, but that is a full circumference around the torso. The armhole is only the stretch of that circumference left open for the sleeve, and if it grew in the same proportion, the sleeve cap would end up out of proportion with the back width and the sleeve length.

That is why the armhole grows fewer millimeters than it would if the bust growth were split into equal parts. Much of that difference is absorbed by the garment's ease, not by the armhole point. The armhole rule is defined separately, looking at how the sleeve cap should end up.

Alignment matters more than matching the exact millimeters

Alignment means the armhole point, the neckline point and the pattern's other references (bust line, center front, side seam) stay lined up with each other from one size to the next, keeping the same proportion of the piece. It matters more than millimeter accuracy: a chart with increments slightly different from another brand's works just as well if alignment is kept, but a chart with the right numbers applied without care for alignment ruins the grade.

The notch (the mark that shows where the sleeve enters the armhole, or where the collar meets the neckline) is where you see most clearly whether alignment was lost: if it is off, the sleeve or the collar stops matching, and the problem shows up only when sewing the sample. To check it, it is enough to overlay the sizes, on paper over a light or on screen in CAD, and confirm that the notch followed the same line as the rest of the outline.

Grading the armhole and neckline by hand, with an increment chart

By hand, you first draw the guide lines (bust line, armhole line, center front) on the base pattern, the fixed reference from which each point is moved. Then you shift each armhole and neckline point the distance given by the increment chart, with a ruler and a square, and redraw the curve with a French curve or hip curve, taking care that it does not lose continuity.

It is accurate if done carefully, but it requires repeating the drawing in each of the eight or nine sizes of the range, and the risk of losing alignment grows with each repetition.

Grading in CAD: the rule is loaded once

In Optitex, Audaces or Gerber the armhole and neckline grading rule is defined once per piece: each point is assigned its horizontal and vertical shift, and the system automatically generates the eight or nine sizes of the range, with the same criterion across all the pieces of the style.

The advantage is not only speed: the program lets you overlay the sizes on screen and check whether alignment holds, something that by hand requires comparing pattern by pattern. Modeltex digital patterns are delivered with this rule already defined and with the full size range graded and approved on a sewn sample, so the armhole and neckline of every size come already solved.

Frequently asked questions

What are the grading rules for the armhole and the neckline?

There is no single rule: each school and each CAD system builds its own chart, but a common guideline deepens the armhole by 5 to 10 mm per size and widens it by 3 to 7 mm, while the neckline grows 3 to 5 mm in width and 1 to 6 mm in drop, more at the front than at the back. Those numbers are adjusted to each manufacturer's real measurement chart and validated with a sewn sample.

How much does the armhole deepen per size?

As a guide, the armhole usually deepens 5 to 10 mm per size, a little more in the extreme sizes (3XL, 4XL). It is not a fixed number: it depends on the type of garment and on each brand's measurement chart, and it should be confirmed with a sewn sample.

How does the neckline grow from one size to the next?

The neckline grows in two directions: width, 3 to 5 mm per size, and drop, which usually grows more at the front (3 to 6 mm) than at the back (1 to 3 mm), because the volume that appears between sizes is concentrated at the front. These are guide values that each manufacturer adjusts to its own measurement chart.

Why does the armhole not grow in the same proportion as the bust girth?

Because the bust girth is a full circumference (it grows 4 to 6 cm per size, as a guide) and the armhole is only the stretch of that circumference left open for the sleeve. If the armhole grew in the same proportion, the sleeve cap would end up out of proportion; much of that difference is absorbed by the garment's ease, not by the armhole point.

What is alignment and why does it matter more than exact millimeters?

Alignment means the armhole point, the neckline point and the pattern's other references stay lined up with each other from one size to the next, without shifting relative to the proportion of the piece. A chart with slightly different increments works just as well if alignment is kept, but a chart with the right numbers applied without care for it makes the sleeve or the collar stop matching when sewn.

Is grading the armhole by hand different from grading it in CAD?

By hand you draw on guide lines and move each point with a ruler and a square, size by size, with more risk of losing alignment the more sizes the range has. In Optitex, Audaces or Gerber the rule is loaded once and the system generates the whole size range; Modeltex patterns already come with this rule solved and the full size range approved on a sewn sample.

More guides

Sewing patterns ready for production, with the full size range, in the Modeltex catalog.