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.

Same band size, different cup size; 32B 32C 32D 32DD 32E
SAME CUP SIZE, DIFFERENT BAND SIZE; 32DD 34D 36C 38B 40A

In theory, to cover a size label range of say UK28A/FF to UK40A/FF (56 bra sizes) you would need to grade 14 cup / cradle sizes and 56 wing sizes!

Why 14 cup / cradle sizes to cover 56 bra sizes? Because (in theory) you can use the same size cup / cradle size in a different band size, it’s called “cross grading”. A 32DD cup holds the same volume as a 34D cup, which holds the same volume as a 36C cup, which holds the same volume as a 38B cup, which holds the same volume as a 40A cup.

Why 56 wing sizes; can wings be cross-graded? NO.

A wing grade / size is unique to one size of bra; you cannot use the wing pattern from a 34D bra for a 36C bra

With reference to sizing table 1 again, here are the main grading increments for a basic underwired bra. With this bra grade you can use the 21mm underwire system for UK retail bras, remember the underwire “grows” in length by 21mm from one size to the next.

If you take the around the body size step of 50mm for the bust as the starting point then it follows that the 50mm must be divided between the front and back of the bra i.e. 25mm for the cups / cradle at the front and 25mm for the wings at the back. The front 25mm is sub-divided into 12.5mm for each cup / cradle half and the back 25mm is sub-divided into 12.5mm for each wing.

 

 

Cup Grading

The important thing to remember is that the cup / cradle increases in size but the wing length gets smaller to maintain the band size.
So a basic Cardinal Point (covered in part 1) grading rule diagram for the cup / cradle grade would be:

 

 

But with each cup / cradle grade you need a wing grade to go with it, to maintain the band size (eight of the 56 wing grades).

 

 

So this grade will give you a “band family” but with different cup sizes, i.e. UK34B, UK34C, UK34D, UK34DD, UK34E, UK34F, UK34FF...

In trying to keep to the rules of maintaining style and function through the grade, one thing you can do is to move the side seams of the bra, were the wing joins the cradle.

For style this keeps the side seams at the sides of the body.

For function this tries to maintain what I term the “stretch to non-stretch component ratio”.

For a good fit, the underwires of the bra must be “sprung open” to fit the breast root curvature; this pulling open of the underwires is achieved by the elastic tension of the stretch fabric and hemming elastics of the wings. So if you alter the length of the wings, you could upset the elastic pull applied to the underwires that was originally designed into the core size bra.

In the cup size grading you are increasing the length of the non-stretch fabric cradle and shortening the length of the stretch fabric wing, or changing the stretch to non-stretch component ratio.

So the revised grading rules for the cradle and wing would be:

 

 

Band or Wing grading

To start you can cross-grade the cup and cradle graded blocks from the last “cup” grade. For example, if you have first cup graded a core size UK34B bra, use the 34C cup and cradle to give you your 36B cup / cradle. The band size of the cradle has already increased by 12.5mm, so to give us a starting 36-band size wing we need to increase the length of the 34C wing by 12.5mm.

 

 

Now you have cup, cradle and wing blocks for a 36B bra we can cup size grade to give us the 36 Band size family of cup sizes. 36B 36C 36D 36DD and so on. Remember to reverse the grading rules to go down in size i.e. to give you your 36A.

You must also remember to check the cup to cradle seam lengths so that the increase in length in grading matches the increase in underwire length for the size steps of the chosen underwires and if necessary alter the cup / cradle grading rules to accommodate the wire length change.

Then continue until you have blocks for all 56 bra sizes! Add seam / hem allowances and start that production run.

One grading rule that you may like to apply to the bra that will help maintain style and functionality, is to increase the depth of the cradle and wings by, say, 3mm per cup size.

 

 

For style this helps keep the “look” proportions of the bra as the size increases. From a functionality point, the deeper cradle helps to stop larger breasts from slipping down out of the cups and the bra “riding-up" in extremes of body movement such as stretching up to reach for something.

Here are some alternative grading rules and the nested grades for an underwired three-panel cupped bra.

 

 

Grading may even apply to the most trivial of details

Think of a ribbon bow sewn to the centre front of a bra. On the designers original bra the size of the chosen bow suited the garment but when the bra is graded up in size the size of the ribbon bow may be to small and become “lost” on the garment. So you may need to specify with the graded patterns that larger bows are to be used on bras above a certain size. This also applies to things such as bra strap widths, hook-and-eye fastenings and findings.

 

Multi-part garments, using percentages to work out grading rules

Referring back to the simple four-panel dress grade. You can work out most grading rules by simply dividing the size increment step uniformly across the parts of the garment, but what if the garment is made up of several parts that are not roughly the same size, and to keep the style / functionality of the garment, the size ratio of the parts to each other must be maintained? The classic example of this type of garment is the corset.

Here are the blocks for half of a core sized UK12 corset that has had waist-reducing “negative ease” already applied. Time to get the calculator out...

Again, you can use Table 1 for the grading size steps. The waist grading increment of 50mm and nape-to-waist (over bust) of 12mm divided by 2. As you are working on the blocks for half the finished garment, you must divide the waist increment by 2 = 25mm or 2.5cm.

First you need to know the width of each panel at the waistline level:

• Panel No.1 = 6.68cm
• Panel No.2 = 8.56cm
• Panel No.3 = 3.67cm
• Panel No.4 = 4.76cm
• Panel No.5 = 4.3cm

Total for half corset = 27.97cm (total corset has a 22inch waist... and breath in!).

The total for half corset needs to increase by 2.5cm = 27.97 + 2.5 = 30.47cm.

You need to work out what percentage of 27.97cm each panel takes.

So 27.97cm divided by 100 = 0.2797. Write the number down or put in the calculator memory.

• Panel No.1 = 6.68cm divided by 0.2797 = 23.88% of 27.79cm
• Panel No.2 = 8.56cm divided by 0.2797 = 30.6% of 27.79cm
• Panel No.3 = 3.67cm divided by 0.2797 = 13.12% of 27.79cm
• Panel No.4 = 4.76cm divided by 0.2797 = 17% of 27.79cm
• Panel No.5 = 4.3cm divided by 0.2797 = 15.4% of 27.79cm

Next, to work out how much to add to each panel...

New half waist size = 30.47cm, 30.47 divided by 100 = 0.3047

• Panel No.1 = 0.3047 times by 23.88% = 7.28cm, grading rule = 7.28 – 6.68 = 0.6cm
• Panel No.2 = 0.3047 times by 30.6% = 9.3cm, grading rule = 9.3 – 8.56 = 0.74cm
• Panel No.3 = 0.3047 times by 13.12% = 4cm, grading rule = 4 – 3.67 = 0.33cm
• Panel No.4 = 0.3047 times by 17% = 5.2cm, grading rule = 5.2 – 4.76 = 0.44cm
• Panel No.5 = 0.3047 times by 15.4% = 4.7cm, grading rule = 4.7 – 4.3 = 0.4cm

Checksum, 0.6 + 0.74 + 0.33 + 0.44 + 0.4 = 2.51cm waist increment step.
(This has got to be a job for an Excel spreadsheet?)

 

So now that you know the waist increment grading rules for each panel, to apply the grading rules to the panels you can use “Shift Grading”

Start with panel No.1. On a sheet of paper draw two vertical parallel lines 6mm apart. At the centre of the two vertical lines draw one horizontal line then below it draw another horizontal parallel line at 6mm (worked out from nape-to-waist).

 

 

Cut a copy of panel No.1 horizontally in half at the waistline and in half vertically about the centre of the waistline.

 

 

Place the four panel parts on the drawn lines and draw around the “corners” of the panel parts.

 

 

Remove the panel parts and draw in the new seam / hem lines from the traced “corners” to give you your first size graded panel.

 

 

For the next size panel No.1, draw two new vertical lines spaced 3mm from the first two vertical lines and draw two new horizontal lines spaced 3mm from the first two horizontal lines. Repeat, new vertical horizontal lines / shifting panel parts / drawing.

 

 

For panel No.2, the first Vertical lines are 7.4mm apart then 3.7mm each side.
For panel No.3, the first Vertical lines are 3.3mm apart then 1.65mm each side.
For panel No.4, the first Vertical lines are 4.4mm apart then 2.2mm each side.
For panel No.5, the first Vertical lines are 4mm apart then 2mm each side.

If you can work with a CAD program, drawing the lines accurately and quickly is so much better.

One thing with panel No.5 is that it has the lacing eyelets at CB marked on it. The vertical spacing of the eyelets needs also to be graded or as the size of the panel increases more eyelet holes may need to be added. Also the busk fastening at the CF needs to increase in length, say every two grade steps, as busk fastenings are supplied in fixed lengths. You do have to think of everything when grading.

When you have a nested grade for each panel, simply trace off the individual size panels and add seam / hem allowance. In her excellent article “Designing & Prototyping Ready-to-Wear Corsetry” Marianne Faulkner also uses a 50mm (2") around the body size step increment.

Another example of a “negative ease” body-shaping garment that you can play the percentage grading game on combined with bra cup grading is an All-in-One body shaper.

 

 

The all-in-one is made up of four main body panel blocks 1, 2, 3 and 4, one inner thigh block 5, a crutch block 6 and three cup panel blocks 7, 8 and 9. Because the garment covers and supports the breasts it is the same as a bra in the fact that it has two size variants and is usually retail labelled in a bra size manner; UK34B and so on.

 

 

So to grade this garment, you can treat the main body panel blocks 1 and 2 as the “cradle” of the bra section and apply horizontal 12.5mm cup grade rules. Also, the body panel blocks 1 and 2 have an association to the waist and hip grade increment of 50mm, as do the main body panels 3 and 4, but you must percentage “share” the increment to keep the size ratio of the panels. As body panels 1 and 2 are graded by the bra cup size grading rules, you will need to grade them first; then use the resultant change in waist measurements to determine the percentage grading of panels 3 and 4.

The inner thigh panel block 5 has a horizontal grading increment of 10mm as the block is approximately 1/3 of the total thigh circumference which usually has a size grade increment of 30mm. However you must take away from this any difference in the measurements of panels 2 and 3 at thigh level after those panels have had a one step grade. The bra cup panels 7, 8 and 9 are cup size graded just like a bra.

The only really tricky part of the garment to grade is the crutch panel 6. It has an association to the main body panels 1,4 and part of 3 as the crutch “connects” to the panels.

You may not be able to keep to the rule of keeping the width of the crutch constant; one trick is to not grade the crutch seam line at the bottom of panel 4.

 

Finally

When grading we must also take in to account and possibly grade any design details / embellishments that are on the core size garment. Remember, we're sticking to our rule of keeping the design's style when grading. For example: a skirt has been designed with two patch pockets on the back, one either side of the centre back seam.

 

 

If we were to grade the skirt up and down in sizes without also grading the size and the positioning of the patch pockets, then the styling of the skirt would be lost in the grade. The pockets would loose their proportions and positioning in relation to the different skirt sizes.

 

 

I have called this article on grading “The Art of Grading” because even with all the maths, number tables and sticking to rules, sometimes you still have to rely on your own judgment and “feel” as to how to undertake certain parts of a grading task. The human body is a beautifully variable entity (thank Mother-Earth for that) and as I always say with design, pattern cutting and grading; “If it looks right, it must be right”. Just keep on checking those seam lengths!!

 

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