Common Trouser Fitting Adjustments

Common fitting adjustments for trousers, pants or shorts - Tilly and the Buttons

Do you like the idea of making trousers or pants, but feel a little nervous about the prospect of fitting them? Well, fear not, as help is here! This blog post will cover the most common fitting adjustments you may need to do when sewing trousers.

We’ve covered a few different fitting adjustments here, but don’t feel like you have to try them all! You may not need to make any alterations to your pattern, or perhaps you feel you need to do just one or two tweaks.

If you’re not sure whether you’ll need to make some alterations, or even what adjustments you might need, it’s a good idea to make a “toile” – a mock-up garment in a similar weight fabric you don’t mind using to test the fit – so you can see how a particular pattern works on you. It’s more important if you’re making something with a close-fitting crotch and bum area, like the Jessa trousers and shorts, but not as vital if you’re making a looser fitting garment, such as the Alexa jumpsuit or playsuit, Marigold jumpsuit or Safiya trousers. Looser fitting trousers have more ease and often lower crotches, making them more forgiving when it comes to fitting – yay! For these types of trousers, you might want to make a “wearable toile”, perhaps in an inexpensive but pretty fabric that you won’t mind wearing if it all works out beautifully.

Ready to dive in and learn how to do some common trouser fitting adjustments? Sure you are! Let’s go…


Lengthening the front crotch

Common fitting adjustments for trousers, pants or shorts - Tilly and the Buttons

If you can see drag lines coming up from the front crotch that resemble smile lines, it may be a sign that it needs more length. On the front leg piece, stick or tape some pattern paper next to the end of the crotch seam and extend the cutting line. A little goes a long way, so around 15mm (5/8in) should make a big difference. With a ruler or steady hand, re-draw the inner leg seam so that it gently tapers into the original cutting line.

Shortening the front crotch

Common fitting adjustments for trousers, pants or shorts - Tilly and the Buttons

If you can see lines dragging down from the front crotch that resemble frown lines, it may be a sign that it needs less length. On the front leg piece, mark around 10mm (3/8in) from the end of the crotch seam and, with a ruler or steady hand, re-draw the inner leg seam so that it gently tapers into this point. Cut away the excess.

A little removed goes a long way with this alteration, so don’t rush into taking off too much – it can be a process of trial and error!

Full booty adjustment

Common fitting adjustments for trousers, pants or shorts - Tilly and the Buttons

If you have a fuller behind (guilty as charged!), you might find that extending the back crotch seam will make the trousers fit better and be more comfortable to sit down in. A good sign that you need to do this is a back waistband that pulls down, and drag lines that come from between your legs.

Cut along one of the lines marked “lengthen or shorten here” on the back leg, from the crotch seam to 15mm (5/8in) away from the side seam. Cut from the side seam to this point so that the two sections are still attached by a tiny pivot point.

Pivot the top section away from the bottom by the amount you would like to increase the crotch seam by – 20mm (3/4in) is a good place to start. Tape or stick down over a strip of paper, and then redraw the crotch seam with a straight line to neaten it out. Cut away the excess.

Small booty adjustment

Common fitting adjustments for trousers, pants or shorts - Tilly and the Buttons

If you have a smaller derrière, you might find that reducing the back crotch seam will make the fit much more flattering. A good sign that you need to do this is drooping drag lines under the bum.

Cut along one of the “lengthen or shorten here”  lines on the back leg from the crotch seam to 15mm (5/8in) from the side seam. Cut from the side seam to this point so that the two sections are still attached by a tiny pivot point.

Pivot the top section over the bottom by the amount you would like to shorten the crotch seam by – 20mm (3/4in) is a good place to start. Tape or stick down and then redraw the crotch seam with a straight line to neaten it out. Cut away the excess.

Saggy back leg adjustment

Common fitting adjustments for trousers, pants or shorts - Tilly and the Buttons

If you don’t feel you have a particularly petite derrière and are still finding excess fabric at the top of your back thighs or underneath your bottom, giving you that delightful “droopy booty” look, it might be that the pattern is too large or long for your thigh. Pin out the excess fabric in the back of your thigh from one side to the other (a sewing buddy or willing family member is helpful for this!) and work through the following adjustment.

Identify where the excess fabric that you’ve pinned is situated on your pattern by measuring down the inner and outer leg seams. Draw a line between these two points on your pattern. Draw a second line starting a third of a way along this line and ending at the crotch seam.

Cut along the second line from the crotch to the first line, and then cut both ways along the first line, ending 15mm (5/8in) from the side seams.

Pivot and overlap the upper pieces over the lower leg by the amount that you pinned out of your toile. Tape or stick down. With a ruler or gentle hand, re-draw both legs and crotch seam to smooth them out.

And that’s it! Remember, don’t get too obsessed or bogged down with trouser fitting. Nobody will be looking at how they’re fitting as they’ll be too busy being mega impressed that you made them yourself!

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Author: Nikki Hoar
Photography: Jane Looker
Model: Alice Irvine

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