How to make trousers that fit: part 3

Now we’re getting somewhere. It’s time to get cracking on that pattern and make up your first toile (muslin).


Whether you take a 2 or a 22, picking the right size can mean one fewer toile in your fitting process so it’s worth re-taking your hip measurement at this point. Make sure you’re measuring around the widest part, that the tape is horizontal and then compare your measurement with the chart.

For trousers (pants for our American cousins), it’s best to go by your hip measurement. We’re going to fit the trousers from the crotch outwards – in all directions – so the waist measurement isn’t as important as the hip.

This week (and it definitely varies during the year…), my hip measurement is 42″ so on this Simplicity chart (Amazing fit trousers 2860), I’d use the size 18.



You might want to trace off the pattern you’re going to use before you start. We’re probably going to be hacking it about quite a bit…

Initial adjustments

There are three things I think you can safely adjust before you make up a toile: the crotch depth, leg length and any grading up or down between sizes at the waist. Each of these alterations can be done pretty accurately based on your measurements, and they’re independent of each other. If you do them now, you won’t have to do an extra toile to get them right later.

  1. Getting the crotch depth right

The crotch depth is the vertical distance between the waistline of the trousers and the crotch. On my Simplicity pattern envelope, it’s helpfully stated that the pattern uses a  waist to hip distance of 9″. I know that my waist to hip distance is 10″, so I’d lengthen the pattern by 1″ at this point.

If your pattern doesn’t state the waist to hip distance, you can measure the pattern pieces to work it out – just remember to subtract all the seam allowances at the waistband.

Most trousers patterns have a marked lengthen/shorten line you can use to adjust the pattern. If yours doesn’t, then pick a spot below the placket opening but above the crotch seam and draw in your own line  perpendicular to the grainline. Use the pattern’s notches to match up your front and back pieces so that you make the alteration in the same place on both.

Already sewn up your toile? Sunni from A Fashionable Stitch has written a great post on how to identify a crotch depth problem from your toile/muslin.

2. Getting the leg length right

This is an easy one to spot, and to alter later on, but you might as well get it right first time, especially for slim fit trousers.

Leg length in trousers is usually quoted in inches, and it’s measured along the inseam of the garment rather than on the body. So if a pair of trousers has a 33″ leg that means the finished garment will measure 33″ along the inseam from the crotch to the hem.

You can measure a pair of trousers from your existing wardrobe and compare these with the inseam of the pattern piece (remembering to take off the seam allowance at the crotch and the hem allowance).

Then lengthen or shorten the pattern pieces at the marked lines (usually at, or above and below, the knee) until it’s the length you want.

3. Grading between sizes

With your waist measurement to hand, go back to the pattern envelope and see if you’re the same pattern size at the waist as at the hip. If not, you might want to grade (taper) up or down a size to get a better fit. For the moment, I’d suggest you only alter the pattern at the side seams and the waistband, and by one size at most. There are other possible reasons for a large size difference here (a sway back or a large abdomen, for example ) and we need to leave ourselves scope to make these alterations if needed.

Tips for an easier fitting process

There are some other things you can try with your toile to make your fitting process easier:

  1. Transfer all the pattern markings, including things like the hip line and knee line, onto your toile. This’ll help you see not only whether those lines are in the right place, but also whether they’re lopsided.
  2. Enlarge the seam allowances from 1.5cm to 2cm or even more if you like so that you have room to try letting the seams out.
  3. Marking the seam allowances on the pattern pieces, and transferring these onto the toile fabric will make it easier to work out your fitting adjustments and to transfer these back to the pattern pieces.

Ready? Set your machine to a nice long basting stitch, thread it up with a contrasting thread, and let’s get to it and sew up the toile!

Missed parts 1 and 2? Catch up here

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