How to fit pants – pattern adjustments 5


From all the basic patterns, pants are the most difficult to fit. It is so because they cover a big part of the body and they pretty much follow all the shapes and curves of the legs, bottom, and waist.

The legs bend at the knees as well as at the hips. On top of that, the shape of the butt and the tummy changes when a person sits. There is a lot of geometry involved here. 

That’s why once you draft the basic pants pattern you might come to the point that it still does need some improvements to get the best fit.

Fitting the pants pattern - most common adjustments

To compare, a skirt must fit only the waist and hips circumference measurements. And the bodice has darts that can change position, width, and length to sculpt the shape of the pattern as close to the body shape as possible.

I want to emphasize that it’s OK to have some wrinkles here and there. You don’t need to eliminate every single one. These wrinkles of fabric give the freedom to sit and move and are usually noticed at the crotch, under the butt and at the back of the knees.

However, there are wrinkles that show some fitting issues. These ones we can adjust and fix by making certain changes to the pattern.

To find out where you might have some fitting issues I strongly suggest you sew a muslin first before cutting some expensive fabric. Each seam in the pants has its own function in making the pants fit well.

Once you sew the pants the fit can still be improved, but you will get results much easier and faster if you work on the pattern itself. That’s why I find this extra step well worth it.

How to fit pants – Full tummy and Full butt adjustment

These are two different fitting issues but with a very similar solution.

When you have a full tummy/buttocks the wrinkles that appear are due to stretching of the fabric in that area.

Let me start with the 

Full tummy adjustment

How to fit pants - full tummy adjustment

How do you know you need a full tummy adjustment?

When you need a full tummy adjustment, it usually looks like diagonal stress lines starting from the belly. The pants front may pull upward, causing the side seams to go forward and the hip area to ride up.

How to fix it:

To make some more room for the tummy, you need some fabric not only in width but in length as well.

Work on the front leg pattern. To make it, draw the high hip line (the hip depth). The high hip is a line leveled with the floor that divides the distance between the waist and the hips. 

Draw another line from the middle knee straight up to the waist. Slash through the lines. When slashing through the hip line, don’t go all the way to the side seam. Leave an inch or 2 unslashed and use the end as a hinge point. 

Spread as much as you need to add. In the general case, approximately 1 inch (2.5 cm) is enough.

Spread the same amount at the vertical and the horizontal line (that would be 1 inch at the horizontal and 1 inch at the vertical). Tape on paper and cut out the new shape.

Don’t forget to adjust the straight grain line if needed. If you have a dart at the front, you may need to shorten it and/or equally divide it into two smaller darts to achieve the best fit.

Full buttocks adjustment

Fitting pants - full buttocks adjustment

How do you know you need a full butt adjustment?

When you need a full butt adjustment, it usually looks like stress lines that point to the back crotch seam. It’s also common that the waistline gets pulled down.

How to fix it:

The solution here is very similar to the one for the full tummy. The difference is that the changes are made to the back pattern piece instead of the front one.

To make it, draw the high hip line. The high hip is a line leveled with the floor that divides the distance between the waist and the hips. 

Draw another line from the middle knee straight up to the waist. Slash through the lines. When slashing through the hip line, don’t go all the way to the side seam. Leave an inch or 2 unslashed and use the end as a hinge point. 

Spread as much as you need to add.

Spread the same amount at the vertical and the horizontal line ( if you need to add 1 inch that would be 1 inch at the horizontal and 1 inch at the vertical). Tape on paper and cut out the new shape.

Don’t forget to adjust the straight grain line if needed.

Note: It’s very unlikely that you need a full butt adjustment AND a full tummy adjustment in the same pattern. If it seems so you most probably need a larger size.

Shorten/lengthen the front crotch

How do you know that you need to shorten the crotch?

The longer the crotch curve, the more fabric there is for the crotch area. If the crotch curve is too long, there is excess fabric at the front crotch area. 

How to fix it:

Work on the front leg. Shorten the front crotch a bit to remove the excess fabric.

how to lengthen/shorten the crotch on a pants pattern

How do you know that you need to lengthen the crotch?

If the pants feel too tight at the crotch and there are smile lines at the front.

How to fix it:

Extend the front crotch and front thigh a bit to accommodate for a longer crotch.

Flat buttocks adjustment

How do you know that you need the flat butt adjustment?

If you need the flat but adjustment, you’ll notice that the pants are baggy at the bum area and there usually are diagonal stress lines starting under the butt and pointing to the outer thighs.

How to fix it:

The back crotch curve is responsible for the amount of fabric in the bum area. To remove the excess fabric here, you need to shorten the curve.

If you don’t want to touch the thighs, the best way to shorten the back seat curve is by cutting through and overlapping in the middle.

Start by drawing the high hip line. The high hip is a line leveled with the floor that divides the distance between the waist and the hips. 

Slash through the line but don’t go all the way to the side seam. Leave an inch or 2 unslashed and use the end as a hinge point. 

Overlap at the back seat curve to remove length and width through the seat. Start with a small adjustment and work your way up if necessary. Small adjustments usually make a big difference.

Fitting pants- flat buttocks adjustment

Low seat adjustment

How do you know that you need the low seat adjustment?

If you need the low seat adjustment, there usually are horizontal stress lines under the butt.

The center back seam dives into the separation between the buttocks. There might be some fabric buckling at the back knees.

How to fix it:

Scoop the crotch curve so that it stands lower. Make a small adjustment at first and increase if needed.

How to fit pants _ low butt and full calf pants adjustment

Full calf adjustment

How do you know you need a full calf adjustment?

The full calf adjustment is needed when the muslin is too tight at the calf. You can also see horizontal stress lines above the back of your knees.

How to fix it:

Work at the back leg pattern piece. Starting at the knee line, draw a vertical straight line at the midpoint and straight to the hemline.

Starting at the mid-knee point, draw two lines at an angle that finish at the sides approximately 4 inches (10 cm) above the knee line.

Slash through those lines and spread as much as you need to add. Tape on paper and redraw the hemline as a straight line.

Full thighs/Thin thighs adjustment

How do you know that you need the full thighs or the thin thighs adjustment?

The crotch curve length determines how close the inseam would be to the body. The back crotch width establishes how close-fitting the pants will be at the buttocks.

If this length is short, the center back seam will pull into the separation of the buttocks. 

If this length is too long, the pants will be baggy under the seat.  

How to fix it:
If you need the full thighs adjustment, add to the back crotch curve and inner thigh area.

If you need the thin thigh adjustment, take in the back inseam.

How to fit pants - full/thin thigs adjustment

Rounded/ flat pubis adjustment

How do you know that you need the round pubis adjustment?

The front crotch length is responsible for how far in from the front of the body the inseam will be. 

If the center front seam digs into the body uncomfortably.

How to fix it:

If the center front seam is too close to the pubis (you get a camel toe), scoop the front crotch curve a bit.

Fitting the pants pattern - camel toe adjustment

How do you know that you need the flat pubis adjustment?

If you need the flat pubis adjustment, there is going to be excess fabric only at the front crotch area.

How to fix it:

If the muslin is baggy at the front crotch, shorten the front crotch curve by raising it up a bit.

These are not all issues that can come up when fitting the pants pattern. However, these are the most common ones that come up when I fit pants. 

If you want to learn more about garment fitting you can read “Pants for real people” by Marta Alto that deals with pants fitting issues. 

Another one that I would recommend and that includes most fitting issues there are (not only pants) is “Fitting and pattern alteration”.

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Some more resources on pattern making for pants:

  1. Make a Knit Pants Pattern And Style It As You Wish
  2. Clothing Design – How to Design Pants
  3. Clothing design – design harem pants from a pants pattern
  4. 3 Easy Ways To Draft a Harem Pants Pattern
  5. How to draft a pants pattern like a pro

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5 thoughts on “How to fit pants – pattern adjustments

  • Lois

    These directions and diagrams are succinct and excellent. Thank you. While I think I knew most of it, nice having it all in one place in a simple presentation that I can print out for reference. I have a gazillion fitting books and documents. Yours is truly excellent. Thanks also for the explanation for “why” the fitting problem is there and thus why the alteration will correct it.

  • Annette Cadosi Wilson

    I have never found pants that fit me well. Because I have a tummy, pants that fit me around the waist are baggy in the thighs (because they are really too big!) and I have a flat bum, so that made for quite a lot of trouble. My mother was a couture type of seamstress, making beautiful clothing that made all the girls jealous when I was in high school. But she could never make pants that fit. 60 years later, I have found the answer! And it’s right here. Thank you so much for this information. Now I can stop wearing leggings all the time, because that’s all that fits me!

  • Lois

    Hi: I was interrupted in my journey through your web site. I did post a comment as I was so very pleased to have found this siet. Today, I spent a portion of this afternoon cruising through many of your tutorials. Wow! They are really good. I have many sewing books, draping, drafting, fitting. I am impressed, and yours are complimentary. Gratias!
    I am just about to have a second My Twin sculpted to use as my sewing buddy. I had one made 20 years ago. Neck to mid thigh with legs. I learned so much about my own body, and about what I need in a mannequin. I will have the new one upper neck to ankle with legs and arms detachable. I call her Priscilla after the old flick Priscilla Queen of the Desert. I am looking forward to applying the wisdom and guidance of your documents as I sew with her for (fingers crossed) and almost perfect fit. Thanks for your support in my sewing adventures.