How to draft a pants pattern like a pro 21

The basic pants pattern is one of the pillars in flat pattern drafting. There are great benefits for both home sewers and clothing designers to know how to draft. But all those numbers and steps to follow are so frustrating, right?

Well, they don’t have to be. Drafting a pattern from measurements doesn’t have to be difficult and intimidating.

You might be thinking:

Why do I need to learn flat pattern drafting and especially how to draft the basic pant sloper? I am not going to lie – flat pattern drafting can be boring and there is simple math involved. This is simply a process of following some monotonous steps of drafting and connecting dots. But it is necessary for any clothing designer. The reason is – it will make your designing efforts easier, not to draft a pants pattern

What is basic pants/trousers flat pattern making?

This is the process of building up an actual sewing pattern that fits certain body measurements. The basic pants sloper is usually used for woven fabrics and has a classic silhouette. There are ways to modify it into various styles according to your designer vision.


this article is about drafting a pattern from custom measurements, not altering a pattern. There is a difference between those two terms. Altering the pattern is a subject we are going to deal with in some of the following tutorials.

Ways to approach drafting the pattern.

There are different approaches to drafting the pattern – some chose to build the front panel first. Then, on top of it to build up the back panel. I prefer to use a method according to which both front and back panels of the pants pattern are drafted simultaneously. This way the pattern is much easier to modify once it is drafted.

You might find another technique more appealing, so feel free to use the one that works best for you. There is no right and wrong here. Also, this is a tutorial on the basics of drafting the pattern. If you would like to get a deeper into the subject and follow up with muslin adjustments and refining the fit, you might find this Patternmaking + Design: The Pants Sloper course useful.

Taking the body measurements.

Taking the body measurements is the first step in the process. It is very important to take the accurate measurements. If
they are not accurate, it might influence the final result significantly.

Measurements and calculations for drafting a flat pants pattern:how to take measure for pants

  • ¼ Waist

Measure the waist at the smallest. Or, if you prefer the pants standing lower on the hips, measure that circumference. Divide it by 4, because we are going to work with 1/4 of the pants details.

  • ¼ Hips

Measure at the widest part of the hips. Again, divide this number by 4.

  • Crotch depth/rise

You can get this measurement by sitting on a chair and holding a ruler next to your hips. Measure from the chair up to where you want those pants to stand.

  • Hip depth

This is the distance between the waist and the hips you just measured.

  • The magic formula. To draw the crotch curve, we will need to know how far we should extend it on both the front and the back pattern detail. There is a simple formula to help us with that.

Front crotch extension formula:                                                           Back crotch extension formula:

15% of ¼ hip                                                                                             45% of ¼ hip

Or, once you’ve calculated the front crotch using the formula above, just multiply it by 3 to get the back crotch.

  • Length

Measure the overall length of the pants on the outer leg. Start from the waist (or a bit lower if you prefer lower rise) and measure down as long as you want the pants to be.

 2. Building the pants/trousers sloper.

2.1 Outline the to draft pants pattern

The first step to take when drafting the pattern is to outline it. We are going to do that by drafting a rectangle as follows:

  • From point A to B, use a half of the hips measurement (or 2 times 1/4 hips). From B to C and from A to D, use the overall length.
  • Divide the rectangle in half so that you get two 1/4 hip wide panels. Mark the points that cross the horizontal lines as 1 and 2. We work with a quarter hip because we are going to draft a front and a back panel. We use each of them twice to cut two fronts and two back pieces of the pants (FIGURE 1). That gives us a total of four details to work with.
  • The next step would be to apply the hip depth. Starting from A and B, apply the hip depth and mark points E and F. Connect them with a dotted line. Mark point 3 where the new line crosses the vertical line in the middle.
  • Again, starting from A and B down, apply the rise and mark points G and H. Connect them with a dotted line. Mark point 4 where the new line crosses the vertical line in the middle.
  • Start from the bottom line and apply the knee level, marking points I and J. Mark point 5 where the new line crosses the vertical line in the middle.

Now that we have the pattern outlined, let’s start

making pants pattern

2.2. Drafting the front panel of the pants pattern.

  • start with measuring 1 inch (2.5 cm) down from point A to point D and mark point K.
  • From point K, measure an inch (2.5 cm) towards the middle and mark it as point L.
  • From point L, apply 1/4 waist measurement and draw a line that connects with the horizontal line of the rectangle. Mark point M.
  • Connect M with 3, and 3 with 4.
  • From point G, extend the line as long as we calculated the front crotch (using the formula above) and mark as point N.
  • from point G, draw a ⅗ inch (1.5 cm) long line at 45-degree angle and mark point O.
  • connect points N and L, passing trough the new point O and E to create the crotch curve.
  • measure 1.2 inches (3 cm) from points 5 and 2 in (on both knee and hemline) and mark points P and Q.
  • connect NID and 4PQ to form the leg shape.
  • connect D and Q to finish the front panel at the hemline.

The last thing we need to do here is to make the lines more natural and smooth as we are used to seeing them on patterns.drafting pants pattern back

We are going to do this in the final step. For now, let’s begin

2.3. Drafting the back panel of the pants pattern

  • Start by measuring 1 inch (2.5 cm) from B towards A and mark point R. From point R, measure another inch (2.5 cm) straight up and mark point S.
  • From point S, apply 1/4 waist measurement plus 1 inch (for the dart) and draw a line that connects with the horizontal line of the rectangle. Mark point T. We are going to draft the dart later. Connect T with 3, and 3 with 4.
  • from point K, extend the line as long as we calculated the back crotch and mark as point V.
  • starting at point K, draw a  1 ¾ inch long line (4.5 cm) at a 45-degree angle.
  • from point F towards B, measure an inch (2.5 cm) and mark point U.
  • connect points S and V, passing trough the end of the 45-degree angle line and the new point U to create the back crotch curve.
  • extend from point M out  ¾ inches (2 cm)and mark point W.
  • do the same from point C out and mark point X.
  • starting at points 5 and 2, measure 1/2 inch (1 cm) in and mark points Y and Z.
  • connect VWX and 4YZ to form the leg.
  • connect Z and X to finish the back panel at the hemline.

    1.3. Final adjustments.making trousers pattern

  • when we drafted the back panel of the pants sloper, we left an inch (2.5 cm) for a dart. To make it, measure and mark the middle between points T and S. Apply half an inch in both directions. Draw a 2 inch (5 cm) long perpendicular line. Connect the end of that line with both sides of the dart. This will result in a dart that is 1-inch deep.
  • now, let’s make the curves of the pattern a bit more natural. Draw a perpendicular line 1/5 inch (0.5 cm) right in the middle of lines O3 and T3. Redraw those lines, making a small curve that passes trough the end of that 1/5 inch (0.5 cm)- long line.
  • do the same with the inner leg lines Q-L and V-W. Instead of drawing the curves out, draw them inwards to make the curves.
  • make sure that the inner leg of the front pattern piece matches the back’s inner leg. If there is a slight difference, just move point V accordingly up or down a little and redraw the back crotch curve.

These were the final steps in drafting a pants/trouser pattern. Please, have in mind that this is the very basic sloper that can be modified in various ways.

You can modify the length and width of the legs, add a zipper fly and pockets, change the depth of the darts, etc. You can also tailor it once you’ve drafted it.

For example, you can remove wrinkles on the crotch or bottom, lengthen or shorten it in the hips area, etc. Here is a good course on that: One Pattern Many Looks

You can also use it as a base for modifications, like a knitted fabric pants, leggings, or harem pants pattern.

Related posts:

  1. Clothing design – design harem pants from a pants pattern
  2. Clothing Design – How to Design Pants
  3. 3 Easy Ways To Draft a Harem Pants Pattern
  4. How to draft a circle skirt pattern
  5. Free Downloadable Sewing Pattern and Sewing Instructions – Harem Pants



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21 thoughts on “How to draft a pants pattern like a pro

  • Gina

    Hi. Thank you for your tutorial it has really helped me gain a better understanding of drafting. Clearly I’m new to this and ran into a problem which I hope you could help me with. I drafted the front pant leg and it came out great but once I started the back I ran out of room. The one forth waist plus the inch runs into the front block. Im not sure what Im doing wrong. If you have any insight it would help so much. Not sure if you need the specs but low rise waist quartered is 12.25 and quarter hip is 12.75. Clearly the numbers are close and even without a dart I cant curve out the hip properly. Again any help would be amazing.

    • Daniela Post author

      Hi, Gina. You might make the dart a bit smaller in order to fit into the panel. But in your case, it is a very small difference and it won’t really matter. If you go over the hip width on the waist, the hip would change the natural line inappropriately. So, I would add the dart to the centre back seam instead of the outer seam. Start from point U up, without going an inch inwards. Then, follow the steps in the tutorial. I hope this helps.

  • Karin

    Nice tutorial.

    I really appreciate that the measurements were given in both inches AND cm, most tutorials I have found are only given in inches (which is not the standard of my country and therefore makes it more complicated for me to use).

    The figures are clear and well marked and well connected to the text. I will definitly try this tutorial to make my first sloper.

    However, I do not appreciate that you write about it being boring in the begining. That nearly had me turning around. This is a skill I want to learn and one which I find intersting both from a crafting perspective and from a mathematical perspective, so I wished you would stop whining and telling me how I should feel about it and just cut to the point of the tutorial.

    • Daniela Post author

      Hey Karin,
      I am glad you appreciate the tutorial. I really give my all to write comprehensive and easy to follow lessons and I usually spend quite some time drawing the figures. So, if I’ve done a good job with that, I’m a happy camper 🙂
      As for the whining part… My heart is in design and I find everything about it fascinating. Even math and the geometrical relations in the human figure.
      However, when I share those “How to draft” lessons with others, I often get the first reaction of frustration about all the numbers and steps involved. The exact words students use are “monotonous” and “boring”. I hear that often, especially from younger folks, who want to skip the drafting part and transform their fashion drawing into a piece of clothing by magic. 🙂
      The words in the intro that bother you are me trying to get pass through that frustration. So, if you would excuse my writing efforts and give the tutorial a try despite it, great!

      • Karin

        This was a very nice tutorial. Glad I tried it before the bodice tutorial I found on another page, having done this made it ieasier to understand the other one too.

    • Daniela Post author

      Hi Erin, this is the basic flat pattern. Everything that comes on top of it, you need to add. That would be seam and hem allowance, zipper fly, etc. I would try with some muslin fabric until I am satisfied with the fit and then move on to more expensive ones. You might also consider if the fabric stretches, how high the waist should be, etc.

  • Nailah parvez

    Hi, fab tutorial many thanks. Just one point i needed help is can i leave out the darts to have it a little roomy or will it affect the rest of the pattern?
    Many thanks

  • Rhonda

    Thank you for the pants pattern tutorial. M y only issue is im trying to sew the pants. In the crotch area how do i go by sewing that correctly? On the front Pants you said to use 15% of 1/4 hip measurement and 45% of 1/4 hip measurement in the back. How would I go by sewing that if the 2 crotch measurements arent the same? The seams arent matching because its 2 different measurments.


    • Daniela Post author

      Hi, when sewing the pants, you should follow the following technology:
      1.Sew the crotch curve on two back pieces together(make the center back seam).
      2. Sew the two front pieces together at the crotch and add the zipper if there is one.
      3. Make the side seams.
      4. Make the center seam between the legs. The inner leg should match exactly on front and back. If there is a difference between the inner leg of the front and the inner leg of the back you would find it hard to match the details. That’s why you need to adjust the inner leg’s length while working on the pattern as shown in the last “final adjustments” step. Let me know if this helps.
      P.S. You may join the facebook group that we started recently so that I could get back too you sooner. Here is the link:

  • Maddy

    The largest part of me nowadays is around my belly, not a around the largest part of my buttocks ! Do I use the largest measurement as hip measurement and would that affect the hip depth ?

    • Daniela Post author

      You use the waist measurement for the waist, but instead of taking in, extend points M and T out. You might want to make the front and back sloper on separate pieces of paper so that they don’t overlap.
      If you use the waist measurement for the hips the pants are going to be too baggy at the hips. If the waist greatly oversizes the hips, you might want to enlarge the hips a bit as well to keep the shapes natural. When the waist is bigger than the hips, I skip the darts as well. Another thing I like to do when sewing pants for that body shape is to add elastic to the center back or sides of the waistband. This way the pants are going to stay in place when you are wearing them. If you are not sure in the results, fit the pattern with a cheap fabric first. Once you make adjustments and approve it, you can make dozens of fitting pants. I hope this helps.

    • Daniela Post author

      Hi Debbie,
      wearing ease is a broad topic that might take another article by itself. Generally, for woven fabrics, the industry standard is 1″ at the waist and 3″ at the hips, which you have to divide and distribute between the 4 details of the pants.
      If you are working with knits, usually you need to subtract some inches which is referred to as a negative ease. On top of that, you need to add some seam allowance to the basic sloper as well.