Adjusting trouser patterns

Today I’m going to explain how I altered the pattern pieces of the pair of trousers I’m making in my Clothes Making class.

First, I took (or remembered from pre-pregnancy days!) the following measurements:

– Waist: Smallest part around body (Diagram A)
– Hip: Widest part of lower body (Diagram A)
– Inside Leg. Top of inside of leg to floor (Diagram A)
– Outside Leg. Waist to floor
– Crotch Depth. Waist to flat surface while sitting (Diagram B)

Women Size Guide

Diagram A

Diagram B

With these measurements I was then able to determine which size of trouser pattern was the nearest match (remembering to allow for any ease included in the pattern), and make any fitting adjustments that were needed.

This is the front trouser pattern piece, after I have adjusted the crotch depth and length of trouser.

Rather than doing it how I did it, length of trouser then crotch depth, you should adjust the crotch depth first. This should be done of the back pattern piece.

On the pattern the crotch line is marked with a horizontal line (pink line). From this line, up to the top of the waistband is the crotch depth.

On this pattern, the waistband is a seperate pattern piece (not shown), and the top of the finished waistband sits 2.5cm below the waist.

This meant that I had to add 2.5cm, and the width of the waistband (minus seam allowance), to the crotch depth on the main pattern piece. After doing all of this, the crotch depth came to 1cm less than my actual measurement, which would mean a very snug fit and the possibility of not being able to sit down!

You should also add 1 – 2cm ease to the crotch depth. In order to make this adjustment, I cut a straight line through the pattern piece, between the top of the pattern piece and the crotch line.

I then spread the pattern open by 2cm (the additional 1cm needed for crotch depth to equal my own, and 1cm ease), and filled it with extra paper. This is the white line you can see in the photo above.

You should ensure that all lines on the pattern (e.g. grain line) still line up now the pattern pieces have been separated.

This alteration should then be done to the front pattern piece as well.

The next step was to alter the length. To do this I used my inside leg measurement, and compared it to the inside leg measurement on the front pattern piece. This is taken from the crotch line downwards, but stopping before the 2.5cm hem allowance.

It seems I am a little bit short, so I had to remove 2cm from the pattern. Most patterns have a horizontal black line indicating where adjustments should be made without altering the overall cut of the garment. Here I folded away 2cm of the pattern to make the trousers the correct length.

This was then repeated for the back pattern piece.

And those were the alterations I made! There are obviously many more that need to be made for a perfect fit, but that’s plenty for a beginners class I think!

Image sources
http://www.houseoffraser.co.uk/General+Sizing+Guides/M162_GENERAL_SIZING_GUIDES,default,pg.html
http://84.243.208.241/~kozomara/index.php?option=com_wrapper&view=wrapper&Itemid=282

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