Sewing Pattern Alteration Pants

Sewing Pattern Alterations – Pants

Here is an easy way to alter your fave pants sewing pattern to make skinny jeans, bootleg trousers, gauchos, harem pants, lounge pants, tracksuit pants, capri pants and many more – all from a pattern that you KNOW already fits your body.

Many people have a hard time fitting a pants pattern to their body.  Fine tuning a pants pattern can require many hours of frustration and much fiddling with muslins and mirrors. It must fit well through the whole waist to hip area and the design of women’s bodies means there is much variation from one woman to the next. These variations in size and curves mean that each of us will have different fit issues to sort out, but once you have done the work required to get a properly fitted TNT (“tried and tested”) pants pattern then you will find that you can take it in many different directions.

So you’ve got a properly fitted pattern and you’ve made a few pairs of trousers and you’re bored– now what? Well, assuming that you don’t gain or lose weight and that your TNT pants pattern keeps fitting you for many years, you may find that fashion is changing even if your body isn’t.

You know that your TNT pants pattern fits and flatters in all the right places but what about the style? Updating a well-fitting pants pattern to change the style is really quite easy.

By changing the shape of the side seams, you can go from classic pants to Marlene Dietrich-style wide legs and know that your pants will still look make your butt look good. Turn your favorite bootleg pants pattern into capri shorts without breaking a sweat, and not a muslin in sight. Remember, you already know it fits you!

Sewing Pattern Alteration - Altering Pants capri


Let’s get started! Grab yourself some tracing paper, pencil, ruler and eraser and lay your trusty pants pattern onto your dining table or cutting table.

Take a good look at the style of your pants and the shape of the side seams and the inseam (the inside leg seam). The possibilities for styling are endless, just by making a few simple changes to these two lines.

The waist, hip and crotch curve part of your pattern all fit you wonderfully so trace that section of your TNT pattern as is, and then we can make some changes to those seams to give you a new style. Classic trousers with a fitted waistband have the side seams blended from the thigh to the hemline for a smooth, continuous line, while bootleg cut pants have a flare added from the knee (or just below) down to the hem. If you want to add some bootleg flare to your leg then you’ll need to work out how much fullness you require at the ankle (eg. 2 inches) measure out from the bottom corners of the pattern, equally on both sides, and add the amount of additional width (eg. 1 inch each side) and mark this on your tracing paper.

Next you will need to think about where on your leg do you want this flare to start. Let’s say you want to add some flare at the knee. Find the knee line on your pattern (measure the distance from your actual knee to ankle point and transfer this to the pattern) and then use a ruler to draw a line down from your knee point to the new width of your pants that you marked earlier (eg. 1 inch wider on each side). Do this on both sides and smooth the area where the flare is added to blend the line in. Remember to make the new hem line slightly curved whenever you add width to a pattern.

Sewing Pattern Alteration - Altering Pants bootleg

Wide leg (or “Marlene Dietrich”) styles are created by extending the side seam and inseam straight down from crotch level to create fullness at the ankle line.

Sewing Pattern Alteration - Altering Pants wide

Want a few more options for wide legs? The gaucho style pant is simply a shortened version of the wide leg pant and the harem pant has elastic or a band at the ankle to blouse all that the fullness up.

Sewing Pattern Alteration - Altering Pants gauchos

What if you want to make your TNT pattern skinny? To reduce the hem width and keep the pants looking good, you will need to keep the straight of grain in the centre of the pant leg and take the same amount of flare out from each side of your pattern.

First, determine the hem width you would like for your skinny pants-– a good way to do this is to take a tape measure and loop it into a circle on the floor and then stand in the little circle. Make the tape measure circle larger or smaller, imagining that it is the width of your pant leg, until you get it right. Mark the hem width onto your pattern and draw a new seam line from the knee down to your skinny hem, blending at the knee to create a smooth line.

A little tip: if you do go very skinny, you may need to add a zipper or button opening for access at the hem, and watch the calf area as you will need enough for easy movement when lifting your leg up or crossing one leg over the other.

Sewing Pattern Alteration - Altering Pants skinny


After all that hard work with your pencil and tracing paper, maybe it’s time to make yourself some comfy lounge pants! Add a little width to the side and inseams and draw a line from the hip straight up to square off the waist. This is done to change a fitted waist to an elastic waistline, which is another easy change to make to your TNT pattern for a bit of easy comfort.

Sewing Pattern Alteration - Altering Pants lounge

Remember that a change in pockets, waistband and cuffs can make each pair of pants you make from your TNT pattern different to the last. Try making your favorite pattern in denim with jeans topstitching, satin with inseam piping, long or short, wide or skinny… The sky really is the limit when you know how to make a few easy changes to your sewing pattern!

Bonfit Pants/Trousers Patterner Book
How to Make Sewing Patterns by Donald H McCunn  

This article was originally written for Women’s Clothing Month at Sew Mama Sew

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Jen Leheny

Hello! I'm the owner, blogger, designer, photographer, maker at Red Instead in Canberra, Australia. I also have a photo portfolio at Jen Leheny Photography and there's some work info at I like to design and make things in my spare time, which I sell at the Red Instead Shop and at Trove Canberra. And in my other spare time, I rollerskate!