The art and science of grading garment patterns as always been a separate entity from that of garment design. A designer would work on a new garment in one size then go to the grader / pattern cutter to have their one size work turned into a size range. At times this process can lead to reworking of a design so that the core size garment can be graded and put in the market place. What if the designer also had knowledge of grading?

So what is grading?

Basically it’s the process of turning a pattern for a garment of one size into other garment sizes but still keeping the original style and function of the designers “prototype” garment.

Style: A designer designs a skirt that has side seams and a centre back zip opening. After grading the skirt pattern to the different sizes, the side seams of the skirts must still fall at the sides of the body and the zip opening must still be at the centre back of the skirts.

Function: A designer designs a bra that fits and supports the bust of the core size model he/she has used to develop the prototype bra on. After grading of the core size bra blocks, the resulting range of different-sized bras must also fit and support the busts of different sized customers.

Core size: The size of the prototype garment that all the other sizes in the range are graded from. Get the core size wrong and the grading process will maintain the errors. In the UK the core size for bra design is still 34”B, even though 34”B is no longer the average bra size in the UK.

Block or Pattern: A block is a garment pattern that has no seam or hem allowances. You should always grade a block, then add allowances to make a working pattern. If you try to grade a pattern that has seam and hem allowances then the allowances will grow with the rest of the pattern.

Example: The cup panels of a bra have been given 5mm seam allowances. If you grade the cup panels with the seam allowance up in size then that 5mm seam allowance also gets bigger.

 

So where to start with the grading game?

You are going to need numbers, lots of them. First you need to set the size range for the garment - if you freelance or work in a company, this may already be set for you “in-house”.

 

Some Size Ranges:

UK8

UK10

UK12

UK14

UK16

UK18

UK20

UK22

UK24

UK30A	UK30B	UK30C	UK30D	UK30DD	UK30E
UK32A	UK32B	UK32C	UK32D	UK32DD	UK32E
UK34A	UK34B	UK34C	UK34D	UK34DD	UK34E
UK36A	UK36B	UK36C	UK36D	UK36DD	UK36E
UK38B	UK38C	UK38D	UK38DD	UK38E	UK38F
UK40B	UK40C	UK40D	UK40DD	UK40E	UK40F
UK42C	UK42D	UK42DD	UK42E	UK42F	UK42FF

XXS

XS

S

M

L

XL

XXL

3XL

 

But what do all the size "labels” relate to and, more importantly for grading, how do the size “steps” change?

A size range starts with “Anthropometrical Data”; in simple words, someone measures a large number of people and works out a set of body sizes that would “reasonably” describe or fit the group of people surveyed. The more people you can survey, the better the size range fit (the more clothes you can sell), and regional variations do play a part. Remember though, anthropometrical data surveys cost money so companies do not do them every year (and some may not have done one for 40 years!).

 

Here are some size range body measurements taken from three different sources (all measurements are in centimetres):

Table 1
Label Size	10	12	14	16	18	20	22
Bust	82	87	92	97	102	107	112
Waist	60	65	70	75	80	85	90
Hips	87	92	97	102	107	112	117
Bust width	17.8	19	20.2	21.4	22.6	23.8	25
Rib cage (underbust)	66	71	76	81	86	91	96
Chest	78.4	82	85.6	89.2	92.8	96.4	100
Nape to waist (over bust)	51.8	53.0	54.2	55.6	56.8	580	59.2
Body rise	27.9	29.0	30.1	31.2	32.3	33.4	34.5
Nape to knee	96.5	98.0	99.5	101.0	102.5	104.0	105.5

 

Table 2
Label Size	8	10	12	14	16	18	20	22
Bust	80	84	88	92	96	100	104	108
Waist	60	64	68	72	76	80	84	88
Hips	86	90	94	98	102	106	110	114
Bust separation	16.8	18	19.2	20.4	21.6	22.8	24	25.2
Rib cage (underbust)	67	71	75	79	83	87	91	96
Chest	74	78	82	86	90	94	98	102
Waist to Knee	58.4	59.2	60	60.8	61.6	62.4	63.2	64
Crutch length	61	63.5	66	68.5	71	73.5	76	78.5

 

Table 3
Label Sizes	6	8	10	12	14	16	18	20
Bust	76	80	84	88	92	96	100	104
Waist	57	61	65	69	73	77	81	85
Hips	81	85	89	93	97	101	105	109
BP to BP	18	18.9	19.8	20.7	21.6	22.5	23.5	24.6
Underbust	62	66	70	74	78	82	86	90
Chest	29.2	30.2	31.2	32.2	33.3	34.4	35.6	37.8
Waist to Crotch	23	24	25	26	27	28	29	30
Waist to Knee	57.5	58	58.5	59	59.5	60	60.5	61
Waist to Bust	15.3	15.5	15.7	15.9	16.1	16.3	16.5	16.7

The first thing you notice is the difference in some body measurements for each size between the three tables. Take the waist measurement for a label size 14 for example:

Table 1 - 70cm, Table 2 - 72cm and Table 3 - 73cm.

This variation is not only indicative of regional differences (Table 1 is intended for the USA and Britain, and Table 3 from Australia) but there is sizing differences between manufacturers. Some companies would argue that their sizing reflects the sizing and preference of their customer base, but in a global e-commerce market we should be looking at some form of standardisation. In Europe the European Clothing Standard EN 13402 has tried to realise this, but the EN13402 Standard is mainly intended for retail garment labelling and there is leeway within the standard for actual measurement variation.

The second important thing you should be seeing in the tables is the size of step between the measurements; this is the important information for grading.

For example:

In Table 1 the waist, bust and hip measurements increase by 5cm per size step.

In Table 2 and table 3 the waist, bust and hip measurements increases by 4cm.

If we concentrate on Table 1 we are given the first main grading step or rule; i.e. the complete waist, bust and hip measurements of the pattern must increase or decrease by 5cm - or a 50mm grade increment.

 

But grading is more complicated than just scaling up a pattern by 5cm. People do not get bigger or smaller by 5cm in every direction.

 

Look at the bust width (bust separation) sizes in Table 1. The measurements change by 1.2cm per size step; a 12mm grade increment to apply to the garments.

The waist, bust and hip measurements are called “around-the-body” for obvious reasons, but what about the “up-and-down” body measurements? The up-and-down measurements are things like height, nape to waist, nape to knee, nape to floor, sleeve length, body rise, crutch length and so on; all "up and down" the body.

Why "up-and-down"? Because we sometimes use the waistline on a block as a 0 datum point and grade the “up-and-down” body measurements from it.

For Table 1 the step change in height is 2.4cm, but for Table 2 and 3 the step change in height is 2.5cm.

Incidentally, one "up-and-down" body measurement that is always missing from a general set of body measurements is the “underbust to waist” measurement, from the breast root under the breast to the natural waist line - which is very important for some intimate apparel garments.

If you design and pattern draft long-line bras, basques (guêpière), corselets, all-in-ones or any body foundation garment that has a “bra” part then the correct underbust to waist measurement makes the garment's waist line sit at the wearer's waist line and the cups of the garment are were they should be - this is very important for strapless numbers.

The underbust to waistline measurement typically is from 11.5cm to 14cm.

For intimate apparel there are some main grading increments that can be extracted from a 5cm around-the-body step size table:

Bust	50mm
Waist	50mm
Hip	50mm
Top hip (11cm below waist)	50mm
Bust width	12mm
Syce depth	6mm
Front body rise	12.5mm
Back body rise	12.5mm

For a 4cm around-the-body step size table:

Bust	40mm
Waist	40mm
Hip	40mm
Top hip (11cm below waist)	40mm
Bust width	12mm
Syce depth	6mm
Front body rise	12.5mm
Back body rise	12.5mm

There are some more grading increments / measurements for particular garments in intimate apparel that you can use. If you are working on underwired bras then you need to know the length and size step of the underwires you intend to use with the bras. There are some variants:

• 21mm system. UK retail bras, the wire increases in length by 21mm for each size step.
• 19mm system. American bras, the wire increases in length by 19mm for each size step.
• 16mm system. Plus fit bras, the wire increases in length by 16mm for each size step.
• 12mm system. Moulded bra cup and bikini styles, the wire increases in length by 12mm for each size step.

 

“Some things never change” or “there’s always a catch 22”.

You do need to do some studying of “Grey’s Anatomy for the fashion conscious”.
If you think of how the body changes with size then there are a few areas or more precisely garment parts / areas / measurements that stay the same size through out the grading process.

Here are two:

Grade an average pair of ladies daywear briefs, Yes, the waist, hip and front/back body rise would change but the width of the crutch should stay the same. Typically the crutch width of this type of garment is 5cm and sticking to our rule of keeping the designs function, the crutch width covers what it needs to cover, so it must carry on doing this function throughout the grading.

,

Next, if you grade a typical bra, the width of the top of the bridge connecting the two cups together is usually 25mm or 32mm. When grading the bra this bridge width must remain constant. So, have a good think about the body and the garment; what changes and what does not when grading from one size to the next?

Okay, so how do you apply the main grading increments (size step changes) to the core size garment blocks? Divide and conquer.

 

Vectors with Magnitudes from a Cardinal’s Point of View.

(Vector = the direction of movement. Magnitude = the amount of movement)

We will first look at a very basic slip dress block and do some simple grading using size Table 1.

You need to identify some key landmarks on the blocks to do the grading from.

The landmarks that you choose will be known as “Cardinal Points”.

Some Cardinal Points are obvious; the “corners” of the blocks. Some Cardinal Points are not so obvious, such as points on the side seams at the waistline and hip. A dart will have three Cardinal Points attached to it; one at the darts origin and one at the end of each dart leg. Be careful with darts, some darts may have had “ease” added to them so the sewing point of the dart may not be the origin of the dart. Make sure also that the dart “legs” remain equal in length after grading - that includes curved darts. The shaped side seams of the dress blocks are, in fact, very long curved darts, so check the lengths after grading.

(How lucky, 26 cardinal points, and 26 letters of the alphabet!)

When you have marked the Cardinal Points on the blocks you need to decide how to move the points, in what direction and by how much. That’s what the arrows and numbers mean. If you see a 0 next to a Cardinal point arrow then that point will not move in the direction when grading. Remember the “width of crutch” example?

Around the body first: As the dress is made up of four approximately equal panels; two front panels centre front seamed and two back panels centre back zipped / seamed, we can simply divide the around the body grading increment step for bust, waist and hips by four. So, 50mm divided by four becomes a 12.5mm increase at each cardinal point; A, B, C, on the front block and K, L and M on the back block. Also, you can apply the 12.5mm movement to points D, I, J on the front block and K, N, on the back block. The movements are all horizontal. For the horizontal movements of the dart points you will use the “bust width” grading step of 12mm. Divide 12mm by two for a 6mm movement on the front block dart points S, T, U, V, and 6mm horizontal movement for dart points W, X, Y, Z on the back block. For points G, H and Q, R use the “chest width” step change of 12mm divided by two, for 6mm movement applied to the front and back.

Now for the up and down movements: Up above the waist line on dress front, points A, F, I, J, S move up by the 6mm nape to waist step and points G, H move up by 6mm nape to waist, plus 3mm from syce depth divided by two; 9mm total.

Up above the waist line on dress back, points K, P, W move up by the 6mm nape to waist step and points Q, R move up by 6mm nape to waist plus 3mm from syce depth divided by two; 9mm total.

Down below the waist line: From nape to hip (9mm) and nape to knee (15mm) you can move C, D, E, V on the front block down by 7.5mm and on the back block move M, N, O, Z down by 7.5mm.

So now you should have a complete grading rule diagram for the dress blocks, and can set to work moving points and drawing new lines.

It is always a good idea to “stack” the graded blocks on top of each other to look for any anomalies in the grading such as curves not staying true (if it looks right). The stack is referred to as a “nested grade”.

Two grade steps from the red line core size (and doesn’t it hurt your eyes!).

 

Next Time

Grading the basic four panel dress blocks was quite straight-forward, but what if the garment has two sizing variants? The classic example of this is the bra; cup size and band or girth size, in combinations of same band size but different cup size, and a cup size with different band sizes.

 

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