by Terry Horlamus
from Threads #101, pp. 66-70

To grade a pattern so it will fit different sizes, refer to the drawings and instructions below and the two charts that follow. For a general explanation of pattern grading, see my article Making Sense of Pattern Grading.

Making the cut
There are five basic pattern pieces: bodice front, bodice back, skirt or pants front, skirt or pants back, and sleeve. Each pattern piece has several vertical and horizontal cut lines, which correspond to measurements on the grading chart.

These drawings show where to cut a pattern so that it can be graded for both circumference (vertical cuts) and length (horizontal cuts). A few simple calculations determine how much to spread/overlap at each cut line.

These standard cut lines are placed in approximate locations where the body "grows" or "shrinks." Vertical cut lines are always parallel to CF or CB (or sleeve's grainline), and horizontal cut lines are perpendicular to CF or CB (or sleeve's grainline). A cut line may pass across a dart but shouldn't intersect a dart lengthwise (this changes size of dart, thereby altering garment's overall shape).

Making the grade
1. Establish overall grade (difference between pattern’s measurements and body measurements).

2. Divide overall grade by 4 to get allocated grade. This distributes overall grade among four parts of body or pattern (left and right front, and left and right back).

3. Divide allocated grade among the cut lines on the pattern piece (see drawings at left) by following cut line’s formula in grading chart on the facing page. Calculate it yourself, or use the precalculated amounts for commonly used grades.

4. Slash along cut lines and spread/overlap by the required amount along each cut line.

5. Blend gaps if pattern was spread; split difference if overlapped. Trace graded piece onto clean paper, and transfer grainline and notches.

Example:
Overall grade: 8 in.
Allocated grade: one-quarter of 8 in. = 2 in.
Formula for line 1 (one-quarter of allocated-grade): one-quarter of 2 in. = 1/2-in. spread

Garment size chart
This chart represents a consensus of pattern company and apparel manufacturer sizing. If you aren’t fitting a specific person, you can use it as a guide for grading up or down.

Base  size	4	6	8	10	12	14	16	18	20
Bust	32	33	34	35-1/2	37	38-1/2	40-1/2	42-1/2	44-1/2
Waist	24	25	26	27-1/2	29	30-1/2	32-1/2	34-1/2	36-1/2
Hip	34	35	36	37-1/2	39	40-1/2	42-1/2	44-1/2	46-1/2

Pattern grading chart
On this chart you’ll find the location of each cut line shown in the drawings, along with the amount to spread/overlap at each for a 1-in., 1 1/2-in., or 2-in. overall grade. In the formula column you’ll see the portion of the allocated grade (AG) distributed to each cut line.

Cut line	Formula	Location	Overall grade (in inches)
			1	1-1/2	2
Bodice front/back
line 1/line 6	1/4 of AG	midpoint of neckline to waist	1/16	3/32	1/8
line 2/line 7	1/4 of AG	shoulder seam to waist	1/16	3/32	1/8
line 3/line 8	1/2 of AG	lower armhole to waist	1/8	3/16	1/4
line 4/line 9	1/4 of AG	CF/CB to armhole	1/16	3/32	1/8
line 5/line 10	1/4 of AG	CF/CB to side seam	1/16	3/32	1/8
Skirt front/back
line 11/line 16	1/4 of AG	waist to hem before dart	1/16	3/32	1/8
line 12/line 17	1/4 of AG	waist to hem before dart	1/16	3/32	1/8
line 13/line 18	1/2 of AG	waist to hem after dart	1/8	3/16	1/4
line 14/line 19	1/2 of AG	CF/CB to side seam a t hipline	1/8	3/16	1/4
line 15/line 20	1/2 of AG	CF/CB to side seam at mid-thigh	1/8	3/16	1/4
Sleeve
line 21	1/4 of AG	between seam and front notch to hem	1/16	3/32	1/8
line 22	1/2 of AG	center line from top of cap to hem	1/8	3/16	1/4
line 23	1/4 of AG	between seam and back notch to hem	1/16	3/32	1/8
line 24	1/4 of AG	midway between biceps and top	1/16	3/32	1/8
line 25	1/4 of AG	midway between biceps and elbow	1/16	3/32	1/8
line 26	1/4 of AG	midway between elbow and hem	1/16	3/32	1/8
Pants front/back
line 27/line 33	1/4 of AG	same as line 11	1/16	3/32	1/8
line 28/line 34	1/4 of AG	same as line 12	1/16	3/32	1/8
line 29/line 35	1/2 of AG	same as line 13	1/8	3/16	1/4
line 30/line 36	1/2 of AG	same as line 14	1/8	3/16	1/4
line 31/line 37	1/2 of AG	same as line 15	1/8	3/16	1/4
line 32	1/2 of AG	midpoint of front crotch extension	1/3	1/2	2/3
line 38	1/2 of AG	midpoint of back crotch extension	1/8	3/16	1/4

Drawings: Linda Boston