Drafting the trousers pattern (2/2)

Once you have finished the most difficult part which was shown in a previous post, you can proceed to the next step: add the waist darts and the ease values.

But before getting into darts, it might be useful to check an important detail: the thighs size. As you might noticed, the basic pattern takes into account the hips size. But if you have large thighs, the theoretical width obtained from the calculations might be too small. Therefore you should measure around each thigh and compare it to the value of the pattern (in green in Figure 1).


If the actual measurement exceeds the theoretical measure with less than 3 cm, you should adjust the pattern as follows (in blue in Figure 1):

  • shift the inside line of the pants from the fork (front and back)
  • shift the outer line of the pants from the hips (on the back)

If the actual measurement exceeds the theoretical measure with more than 3 cm, you should adjust the pattern as follows (in red in Figure 2):

  • increase the crotch depth and shift the inner line of the pants (front and back)
  • decrease the crotch width (on the front)


Once you have corrected your pattern, you can proceed to the following step.

To add darts to the waist, you need to calculate the value to absorb = hips size – waist size. This value is to be divided like this:

Value to absorb = 2 x back darts + 2 x front darts + 2 x side darts + 1 center front dart

This is a rather general formula and you might need to adapt it to your body shape:

If you have a small waist but proeminent hips, you can create several darts for the front and the back, knowing that, the closer you are from the side, the lower the value of darts will be. On the contrary, if the difference between your waist and your hips is not very high (less than 15 cm), you can avoid the front darts. The value of a front dart can not exceed 2 cm. The front darts are created on the center line and then to the sides, half way between the center line and the side line (Figure 3).


If you’re more curved on the back and have a flat tummy, you might need to increase the value of the back darts. The value of a back dart should not exceed 2.5 cm. If you want to absorb more than these 2.5 cm, you need to create more back darts and place them at one third and two thirds of the width from the side line (Figure 3).

If your belly is not as fit as you wished to, it might be useful to lower the front waist line and increase the center front dart. The value of this dart is 1 to 1.5 cm and will be deffinitively set when you try on the test trousers (Figure 4).


The back side dart was set at 1.5 cm during the pattern construction. It must have the same value and the same shape as the front side dart (in red). If you need to absorb more value on the sides, first change the back side line and then transfer the new line on the side front (in blue in figure 5).


The pattern you just created is the basic shell and you must keep it safely for future trousers pattern alterations.

If you want to test this pattern (which is strongly recommended), you need to add the minimum values of ease and then cut the pattern in a cotton cloth to make final adjustments on your body, adjustments that I described here.

Here are minimum adjustments to add to your basic pants (Figure 6):

  • ease to waistline = 2 cm. As the pattern is built by quarter (two front and two back pieces), you should add 2/4 = 0.5 cm on each side
  • ease to hips = 4 cm. Add 1 cm to the hips on front and back side
  • increase the crotch depth with 1.5 cm on the front and back pattern
  • ease to knees = 4 cm. Add 1 cm at the knees on front and back pattern


You need to set the ease values depending on the model you choose and the fabric you use (stretch, light or heavy).

You now have the necessary elements to create your tailored trousers (you can build pleated trousers for example). Do not hesitate to give me a feedback on this method which is inspired from the book of Teresa Gilewska, “The Fashion Pattern-Making, Volume 2”. From now on, draft beautiful pants.


23 thoughts on “Drafting the trousers pattern (2/2)”

  1. crotch length increased by 1/2 inch now baggy / extra fabric in thigh area. Is there a way to increase crotch length w/o increasing thigh circumference ?

    • hi Ann, in my article I showed how to addapt the pattern if you have large thighs, but your problem seems different, so before answering, can I ask you why you add 1/2 inch to the crotch length?

    • Seam allowances wouldn’t be included in these, but you just need to add the desired amount all around when you trace/cut out your fabric (or retrace a separate copy of your finished with the added seam allowance, so you won’t have to do it every time).
      Commercial patterns like ‘Simplicity’ tend to use 5/8″ (1.5cm) seam allowance, but I usually just give it about 1/2″ or even 1/4″ sometimes, which is generally the width of the presser foot on your sewing machine.

  2. Please , can this method be used for drafting kids pant pattern as well.
    And can one use elastic band waist with this method ,if yes, How do one provide for that .


    • hello, this method is quite complicated for kids, I think pants pattern for kids are simpler that that. you can add of course a waistband but it is not I would suggest as this pattern is made to be fitted

  3. Hello! Thank you!
    My question is: what does the resulting clothing piece look like? Is there a picture example?

    I’m asking because I want to make high-waisted trousers, that really hug my waistline. This is important because I just spend a month or so on pants that were seemingly ‘high’ waisted but turned out to hug my hips instead :O haha, no big problem, but I just want to get it right this time.


  4. Thanks for the detailed and simplified description. If I am to add a zipper, please what adjustment would need on my crotch.

  5. Here’s a thought…from a not very experienced sewist, so please forgive me if it sounds stupid.. Why not add whatever ease you normally like to have at your waist , hips and/or thighs to your measurements and draft the pattern in one go? Unlike a bodice sloper, which might be subjectt to any number of style variations, pants in general are not. Except, of course when you add pockets or yokes and such.

    • it is a good question, you can do this way if you are going to keep pretty much the same ease for all your models and you won’t alter them that much. anyway, when you make a pant that fits you well, the pattern is always a good starting point for another model.

    • It can be some standard measures but measuring crotch depth is the best option

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