Before you start designing a garment, you'll need to use your measurements to draw the basic block to size, including the desired reduction rate. All garments such as swimwear, bodysuits, dancewear, leggings, etc. are made from blocks. Knowing how to create a block is essential if you want to create a clothing line, for example, or start modelling.

The bust block is a 2D representation of the bust. The bust extends from the base of the neck and shoulders to the crotch. It includes a chest clip for a perfect fit.

But you can also create a block for sleeves, legs, etc.

For the lingerie sector, it will be necessary to integrate the different reduction coefficients to obtain a block with a reduction coefficient. You will therefore obtain specific blocks for each swimming costume, bodysuit, etc. application and type of fabric.

Commentary:

I will be working with CAD software but using the same methodology as in paper format with ruler, pencil, ... In CAD certain steps can be simplified by drawing rectangles, duplicating steps, ...

Step 1: Measurements

What are your measurements?

The following measures will be necessary

Circumference below chest 78cm
Chest circumference 88cm
Waist 68cm
Hip circumference 93cm
Distance waist to chest: 16cm
Distance from waist to hips: 26cm
Fork distance (waist to waist): 72cm
Distance chest to chest: 20cm
Distance from neck to waist: 38cm
Back length: 34.5cm
Neckline: 37cm
Shoulder length: 12.2cm
Shoulder to chest distance: 24cm

In our example, we'll use the measurements for size 38 from the size chart.

If you're creating your own block using your own measurements, follow the same steps as above, but using your own measurements.

Step 2: The discount rate

There is a specific article on choosing the discount rate. I strongly suggest that you consult it.

In the example I will apply a reduction rate of 12% horizontally and 0% vertically.

Step 3: Positioning the parts and axes

Before we start, we're going to begin by positioning the parts that make up the block and different the main lines and axes.

The block will include the front and back and each time we will represent half of each bust (see middle front and back axes).

As in our example we have opted for a vertical reduction rate of zero, all the "vertical" distances should be taken as they are without correction.

Draw the 2 axes - 2 vertical lines, leaving enough space to the right of each of them

the mid-back axis (A)

the centre line in front (B)

Draw horizontal lines such as the waistline, the underside of the chest, the hips, etc.

Start by drawing the size line (LT), which will be our zero reference frame (leaving room above and below for the following steps).

Then draw :

Chest line (LP) = distance waist - chest line from waist line

the hip line (LH) = the distance between the waist and hips in relation to the waist line (LH)

the front (LC) and back (LN) lines on the front and back blocks respectively

The next step is to draw the line on which the high point of the shoulders will be positioned

This line is placed at a distance of 1.8cm above the nape of the neck, to which 0.1cm is added every 2cm when the distance between the waist and the nape of the neck is greater than 32cm.

In our example the distance from the waist to the nape of the neck is 38cm-> (38-32)/2cm = 3

The distance is therefore 1.8 +0.1×3 = 1.8 +0.3 = 2.1cm

Draw a line (LE) 2.1cm above the neck line (LN)

The next line (LF) is a little more specific; it concerns the position of the crotch - a line which will be positioned in the middle of the bottom of the trousers.

In reality, the position depends on your body type, the type of clothing you are wearing and the size of the bottom of your panties.

Half of the panty bottom is equal to the fork/2 - distance waist - hips

In our example: 72/2 - 26 = 36-26 = 10cm

But the bottom of the trousers will be subjected to vertical stress, and will have to stretch when worn. We will therefore apply a reduction rate. This rate can be from 8% (for high-waisted knickers) to 20% (for a thong).

For a 1-piece swimming costume, take 15% for example.

The length of the 1/2 bottom is therefore: 10 x 0.85 = 8.5cm

Draw the line (LF) at a distance of 8.5cm below (LH)

Step 4: drawing the back - lower part below the waist line

We're going to start placing horizontal points.

As the pattern will be produced with a horizontal reduction rate, a correction must be applied to the various values before the points are placed on the plan.

Before we start, we're going to place some points that will help in the construction of the block

points 1, 2 and 3 where the waist, hip and 1/2 bottom lines intersect with the mid-back axis

Size: point 4

distance (1-4) = waist circumference /4 x 0.88 = 68 /4 x 0.88 = 17 x 0.88 = 14.96cm

Hip circumference: point 5

For the hips, the reduction rate can be adapted according to the design of the garment, the morphology or the desired result. To avoid the effect of a bikini sliding down the buttocks, the reduction rate can be halved (i.e. 6%).

distance (2-5) = hip circumference /4 x 0.94 = 93/4 x 0.94 = 21.85cm

point 6

Draw the line (4-5) and place point 6 equidistant (in the middle).

point 7

Draw the line (2-5) and place point 7 equidistant (in the middle).

point 8

Draw line (6-7) and extend it until it intersects with line (LF); position point 8 at the intersection.

Step 5: design the front - lower part below the waist line

Before starting, we are going to place some points which will help in the construction of the block as for the back.

points 9, 10 and 11 where the waist, hip and 1/2 bottom lines intersect with the centre front line

Size: point 12

the distance [9-12] = the distance [1-4].

Hip circumference: point 13

the distance [10-13] = the distance [2-5].

Point 14

Draw the segment [12-13] and place point 14 in the middle.

Point 16

Draw a line parallel to line (LT) through point 14. Point 15 is located at the intersection with the middle axis in front of

Point 16 is located at a distance of 1/3 [14-15] from point 14.

Point 17

Point 17 corresponds to the inflection point of the bottom of the panties. It depends on :

style (high-waisted knickers / shorts)

-the "safety" or comfort sought

A good compromise is 7cm. As we are representing the 1/2 pattern in relation to the axis of symmetry, we will represent 3.5cm on the pattern.

Point 17 will therefore be located on the line (LH) 3.5cm from point 10.

Point 18

the distance [11-18] = the distance [3-8].

Draw the straight lines connecting 16-17-18

Step 6: Front and back - breast point

First of all, we are going to represent front and back width to chest size

For stretch garments: 52.5% on the front and 47.5% on the back.

For the front

(chest size /4)*reduction rate *distribution in front = (chest size /4)*0.88*1.025 = 88/4*0.88*1.025 = 19.84cm

For the back

(chest size /4)*reduction rate *back distribution = (chest size /4)*0.88*0.975 = 88/4*0.88*0.975 = 18.88cm

Draw 2 parallels to the axes (one parallel for the front and one for the back) at respective distances from the axes of the distances calculated above.

The chest: point A

Point A is located on the chest line (LP) at the distance: (distance chest - chest)/2 * reduction rate = 20/2 *0.88 = 8.8cm

Step 7: The breast clip

To define the chest clip, we will start with the waist clip (between the chest and waist) - 4 clips, 2 on the front and 2 on the back.

distance from base of clip = chest circumference *1.025 /4 - waist circumference /4 =88*1.025/4 - 68/4 = 5.55cm

Length of clip = distance chest to waist = 16cm

Draw the clamp

Place the forceps horizontally on the breast line, with the tip positioned on the point of the breast.

Place points 19 and 20 at the intersection of the vertical line drawn above and the chest clip

Step 8: The shoulder line

On the back :

Point 35 is perpendicular to the mid-back axis and distant from point 32 by 1/6 x the neckline = 37/6 = 6.2cm

Le point 36

Point 36 is distant from point 35 by shoulder length x reduction rate = 12.2*0.88 = 10.74cm and is located at the intersection of line (LN)

On the front block :

Points 30 and 31:

Point 30: at the intersection of the neck line (LN) with the centre line in front.

Point 31: at the intersection of the line (LE) and the backbone axis

Point 32

Position point 32 3.75cm vertically from point 30.

Points 33, 34 and 35

Point 33 is perpendicular to the centre front axis and distant from point 32 by 1/6 x neckline = 37/6 = 6.2cm

Point 34 is located on the front axis and is 1/6 x neckline away from point 32.

Point 37

This is the counterpart of point 36 on the back block.

Point 37 is distant from point 33 by the shoulder length x reduction rate = 12.2*0.88 = 10.74cm, respecting the same orientation of the shoulder on the front and back ([33-37] is parallel to [35-36]).

Step 9: Side line adjustment - from waist to armhole

The length [12-19] to the armhole should be extended by the length: [middle shoulder to point of chest] x 1/8 (give or take a few millimetres) = 25cm / 8 = 3.12cm

Point 40:

Extend [12-19] by 3.12cm

Point 41 :

Measure the length [12-40] =18cm

Place point 41 on the back block on the vertical line (C) at a distance of 18cm from point 4.

On the front block, we're going to move point 40 to accommodate the chest clip.

Draw A - 19 - 40 and rotate the set with respect to point A. Point 40 moves to point 40′.

Draw right angles at points 36, 37, 40′ and 41

Step 10: Adjusting the breast height

In step 9 we measured the length from the middle of the shoulder to the point of the chest.

Measure the actual measurements on the mannequin and adjust the pattern.

As an example, I'm going to show you before and after correction.

To be honest ... it's at times like these that I don't regret making my plans in CAD.

Step 11: Final tracing of the block

You then need to check that the parts fit against each other to ensure that the joints have smooth curves.

Also check the lengths of the side lines on the front and back, which must be exactly the same.

I strongly suggest that you make a prototype to validate your block so that you can modify it if necessary. It will be that much easier to create templates.

If you already have your bust/block at actual size?

It's more or less the same process, but you take each anchor point and apply the horizontal (and vertical if necessary) reduction rate to it.

In the example I will use, I will only apply a horizontal reduction rate of 15%, while the vertical reduction rate will be 0%.

I suggest not applying a horizontal reduction rate to the stitches forming the neckline (33,35,34) but also to the gusset with stitch 17.

Size: points 4 and 12

Measure [1-4] and [9-12] and apply the reduction rate

[1-4] x 0.85 = 15 x 0.85 = 12.75cm

Place the points 4′ and 12′

The hips

Proceed in the same way for points 6 and 14

The chest

Do the same for point A and redraw the clamp

Armhole

Proceed in the same way for points 40′ and 41, then 36 and 37.

Join all the stitches by tracing the curves of the armholes, thighs, neckline and side line.

Your bust with reduction rate is finished

As with the previous version, I suggest you create a prototype to identify any corrections that need to be made.