Pants Fitting: The Crotch Part 2

Part 2- Comparing those measurements to the pattern.

(In case you missed it please read part 1 before you continue.)

Now the fun part… comparing those measurements to a pattern.

** Disclaimer: This blog post will not cover picking the right size or anything else that is not related to the crotch curve of the pants. We will only be covering how to use those crotch specific measurements taken from part 1 and compare them to the pattern. This is for woven patterns only.

Things to note before we start…

  1. The measurements taken for the crotch hook are taken from the middle of the leg. Assuming that the inseam will fall in the middle of the leg. Not all pants are drafted to have the inseam fall directly in the middle. Sometimes the inseam could fall more towards the front. One example of this is fitted jeans. Take note of this by looking at some modeled pictures of the pattern. Either way, focus on the saddle’s total. (Saddle: total seat width.)
  2. I have given you an order in which to check/adjust these measurements (Crotch Hook, Crotch Length, and last Crotch Depth) on a pattern. The reason why it’s so important to do it in this order is that each measurement/adjustment will affect the next one. You will see when you start adjusting. To be honest, crotch depth is not the most pressing measurement to compare because whatever you do to the crotch length does also affect the crotch depth. I still list it as the last thing to check even though I encourage people not to worry too much about crotch depth. The only time where you can really see issues arise with the crotch depth is when the model drafted height is considerably different from yours.


(Here is a link to an Instagram highlight I saved showing how to.)

Step 1. Draw your seam allowances or stitching line.

I encourage you to do this because not only will it show you were exactly the pattern itself is, but we need to draw out more lines later and accuracy is important.

Purple outline is the stitching line and center front.


Step 2. Draw the crotch level

This is a line from the crotch hook tip to the side seam. It must be perfectly squared and perpendicular to the grainline. (Green line is the crotch level)


Step 3. Check the crotch hook/extension for front and back with L shape ruler.

(When I am referring to places where the ruler should touch, I am referring to the inside of the L shape ruler. This is the area where the ruler touched your body.)

Place the bottom of the L shaper ruler on the crotch level. Then, scoot the side of the ruler until it touches the center front or center back. The ruler must be level and not tilted.

Green marking on a ruler is my front hook measurement. Purple is my back. We are working on the front pattern piece.

Step 4: Check to see if the crotch hook tip matches your measurement.

If it does: leave it

If it doesn’t and the pattern hook is too short … extend it.

If it doesn’t and the patterns hook is too long … shorten it.

BEFORE YOU ADJUST… check both front and back hooks. This goes back to the point I made earlier that sometimes the inseam will not fall directly in the middle of your leg. Take note of your total hook width and compare it to the patterns total hook width. Then you can make the decision of where to add/subtract.

In this picture, the hook tip is 1/4″ too short from my front green marking.

How I would extend it.

Crotch hook

Step 5. Measure crotch length.

This is where ease is taken to account. Each pant style has a different amount of ease added to the crotch length. (Amount of ease is up to the discretion of the pattern maker. Usually, you will not find this noted in a pattern so the following are a general estimate of ease in the crotch length.)

Your Aim: Your crotch length + Ease = Total crotch length on pattern.

Amount of ease:

(This amount is divided evenly to front and back.)

Fitted jeans- 0″

Slacks: 1/2″-3/4″

Trousers: 1″

Jumpsuit, culottes: 1-1.5″

Measure the crotch curve of the pattern after you adjusted the crotch hook and compare that measurement to your ideal length.

***Consider also where the top of the waistband should be hitting. Is the pattern intended rise at the waist (high rise)? Is it midrise? Low rise?***

If you need to remove or add to crotch length, make a wedge adjustment hinging from the side seam. (See purple line below. Around hip level.)

Warning… if your length with ease is more/less than 1.75″-2+” of difference. Check your crotch depth next before deciding to adjust the length. This goes back to the point where I said that crotch depth and length go hand in hand and affect each other.


Step 6. Double-check crotch depth.

Crotch depth is measured from waistline to crotch level on a pattern of the front pattern piece. Crotch depth also has ease depending on pant style, usually around the same amount as the crotch length. (See above for amounts, I usually like to keep it around 3/4″-1″ ease)

Your Aim: Your crotch depth + ease = pattern crotch depth

If you have noticed a considerable difference for the crotch length in step 5 this is when you would check the crotch depth and more often you will notice a big difference in crotch depth on the pattern. If so, adjust and check crotch length again

The picture below: I had noticed that the crotch length of this pattern was 3-4″ different than my aimed length. So I checked the crotch depth, and even with ease, there was a big difference in the depth. (Blue marking on ruler is my waist line.)

Adjustments to the crotch depth are made in the same area as the crotch length. But instead of a wedge, you will completely take off the length. Equal amount across the whole pattern.

Picture above:

I removed crotch depth to the aimed amount. Then remeasured the length again and it (the length) ended up being exactly where I wanted it.

All done.



1. Crotch hook/extension

2. Crotch length with ease

3. Crotch depth with ease.

4. Lines are trued and pattern pieces are walked.

5. The hook point is at a right angle and not pointy.

Now tissue fit or muslin. Thank you for reading!

***This post is not sponsored. None of the companies of the pattern shown are in collaboration.

Part 3 in the series will be next on the blog if I receive any FAQ regarding this topic.

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  1. I see that you take make these comparisons without the patterns waistband attached, is there a reason for that? I would assume that you take it into account when checking crotch length/depth.


    1. Hi!
      The crotch length and depth is measured from waistline. So I would have to measure from waistline to end point. If that involves the waistband then yes but not all styles include a waistband or the waistline is located in a waistband. The key point I want people to remember is to always measure from waistline to end point or seat. Hope that makes sense and thank you for reading 💕.


  2. Is the crotch curve shape not so fundamental after all? Or there is no easy method to find that shape out? I was wondering why it is not mentioned in this tutorial 🙂


    1. No (not really) because there shape is only different for the type of style you are drafting for. If you were to compare jeans, trouser, slack etc you can see the shape/angle of curve is slightly different. What makes the pattern to accommodate the front or your back end is the length. Plus there are guidelines pattern makers use to prevent the curve from dipping too low to prevent a unibottom look. A visual probably would explain it better.


  3. This is very informative. RTW pants almost always have too much crotch depth AND crotch length, which is why i’m learning to sew my own pants. Should I tackle both problems together or focus on one first?


      1. When both the crotch depth and crotch length are too big/long, which alteration should I work on first?


      2. In the blog I explained the order which each fit point should be done first. They should be done in that order because one will affect the other. I would start with the first step which is the crotch hook.


  4. I’m going to go through these steps, but fitting panties I’ve discovered I’m one of the 5% with a pelvis that is a wide shallow oval, and I have to shorten crotch piece back to front by 5/8″ and widen 5/8″ each side. I would have thought the shallow crotch would correspond to short crotch hook on trousers as you measure it, but in practice I have to lengthen the crotch at the inside leg seam for pants not to pull. I also do lots of measuring, and love the details you provide. I will try this and report back.


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