Some basic knowledge of pattern-making may be useful.

We have written a special article to familiarise you with the basics of patronage

In order to be able to accurately adapt a pattern designed for a stretch garment, it is important to :

• know the size chart
• position the parts in relation to the reference frame: axes, ...
• know the reduction rate(s) used when designing the garment

Size chart

The more information you provide in the size chart attached to the pattern, the easier it will be to adapt the pattern to your measurements and body shape.

For each size, you need to know :

• waist circumference* (in centimetres)
• Hip circumference
• Chest size **
• cup size - chest size** (in mm)

Other data are also very useful:

• waist - hip
• Chest - Waist**
• chest distance** (mm)
• ….

* for lower bust parts

** for upper bust pieces

The list is not exhaustive. Depending on your morphology, certain data may be of interest: fork length, back width, anteversion/retroversion .... But we'll look at the specifics in a future article.

The first step is to identify any discrepancies between the measurements you take and the measurements on the size chart attached to the pattern. So before modifying a pattern, be sure to:

1-take your measurements accurately

2-choose the size from the size chart attached to the pattern that is closest to yours

3-identify significant differences

 

The frame of reference

This can sometimes be complicated. The reference points are not always indicated on commercial patterns.

The axes to be positioned :

• the front and back centre line (the easiest!)
• the position of the tip of the chest - the apex

Lines to be positioned :

• waistline
• hip line
• under-chest line or chest line
• inflection line front and back

Depending on the adaptations to be made, the benchmarks will be more or less relevant to identify.

For example:

Your waist circumference is 8cm larger than the waist circumference indicated in the pattern size chart - the other data being consistent with the chart.

The only difference identified is therefore the waistline -> in this case it will only be necessary to identify the position of the waistline on the different pieces of the pattern.

 

The rate of reduction

I'm sorry it's not always specified on patterns sold in shops. In fact, this is rarely the case: shame!

If it is not specified on the pattern or the instructions attached to the pattern, you can estimate it empirically. But you need to know the measurements on the pattern design chart.

Let's take the following example: a 1-piece swimming costume pattern made with a horizontal reduction

Example for a size 38 with a waist measurement of 68cm

Measure and calculate the waist circumference of the pattern: (A+B) x 2

Waist size of pattern (example): 57.8cm

Calculate the reduction rate: 1-(57.8/68) = 0.15 i.e. 15%

 

It's possible to do the same for verticality, but for me it's much more complicated. Why should I do this?

• vertical measurements are rarely specified in the attached size charts
• how can you be sure that the pattern has been reduced vertically and whether or not it has been done evenly? and that's another story.

 

But frankly I wouldn't try to recalculate a vertical reduction rate. In fact, it's stature that has a significant impact on the verticality of a pattern for a given size.