How to adjust trousers, Part 1

Having fitted pants, which perfectly falls down without pleats, is by far a great achievement in your sewing life. Whether you start with a homemade pattern or a commercial one, you might have to make some adjustments when trying on your pants.

First put on your pants with fitted shoes and ask a friend to check how the pants are falling in the back.

Some adjustments can be made directly on already sewn pants, others require having built test trousers before. If you are never satisfied with pants found in stores, I suggest you to do a pair of test trousers that you will keep as a basis for future pants.

First and foremost, here’s a picture to illustrate the most often used terms (Figure 1)

  • mid back seam (pink)
  • side seams (blue)
  • legs internal back seams (green)
  • the belt seam (orange)


Annoying situations can occur during the fittings. Here is how to fix it:

1. Slanting folds appear under the buttocks (Figure 2). You need to curve the pants crotch.


On your sewn pants, pin the excess fabric to form an horizontal fold on one leg (Figure 3).


Unseam the mid back seam. Slide the two legs into each other, right sides facing, the folded leg over the unfolded leg. Pin the legs together, gently pulling up the excess length on the unfolded leg (Figure 4).


Mark with pins the original mid-back seam of the folded leg on the other leg (Figure 5). Baste stitch this line on the unfolded leg only (Figure 5).


Remove all pins and sew the two legs along this new mid-back seam, re-cut the seam (Figure 6).


2. The pants are too tight on the buttocks, the belt goes down in the back and side seams are pulled back (Figure 7). You need to add fullness on behind.


If trousers are already sewn, you can add wideness on the side seams or on the legs internal back seams.

If you made test trousers, cut them where your behind is the strongest, vertically from the belt to the knee and horizontally from one side seam to another.

Pin the slot edges on additional fabric strips (Figure 8).


3. The trousers crotch is too tight (Figure 9).


If trousers are already sewn, give extra length on legs internal back seams and curve the crotch line. Try them on before cutting the excess fabric.

If you made test trousers, cut them crosswise from one side seam to another, add extra fabric strips and pin the slot edges on fabric strips (Figure 10). If necessary, give more comfort on legs internal back seams.


Your case is not among the three mentioned above? Don’t panic, the second and third parts are on my schedule.


18 thoughts on “How to adjust trousers, Part 1”

  1. Thank you so much 🙂 You have done a great job of making sewing so easy to understand.

  2. Very useful information. I’m looking for info about making pants into a skirt..Would you havew this info?

    • Hi Gladys, do you mean transforming a skirt into trousers? Well, no, but it could be an idea to explore

  3. Um wow! I have just finished a some pants for my daughter who is heavy set, and even with all my alterations they are better but still have issues. Even though I have a ton of pattern drafting books and at least 3 devoted to fitting issues I still could not understand what I was doing wrong. These articles point out the problem, and show me what to do in an easy to understand way. Thank you very much!!

  4. Thank you so much for the help. The fog is clearing now. Maybe I can salvage a few pair of pants started and never finished because of fitting issues. With a prominent stomach and a long crotch length, I was having fits trying to fit.

  5. This really helps to see the visual!! I am extremely swayback and have an ample bum! No matter what I weigh, this has always been a challenge to tweak in pant patterns. Thanks so much and if you happen to have any suggestions, please let me know.

  6. Adorei as explicaçoes pretendendo utilizar para tornar minhas calças perfeitas, muito obrigada

  7. Hi
    I find your pins so helpful!
    I just went to a sewing expo and one of the teachers told me I have a low seat and right buns! I am working on my 2 muslin and curved the back in a j, but it is frowning, and I folded up another inch on the front. What else would you suggest ?

  8. I am having trouble with ready made pants pleating diagonally from above the knees to the top of legs in the front of my pants, when when I walk. I can pinch and pin out fullness of the fabric under my fly front across my body, then the pleats go away. What can I do with this annoying problem? Hopefully, you are the answer to my prayers.

    • hello pat, if i understand well, you have already found the answer to your problem? i.e. pin out fullness under your fly front?

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