Trousers alterations

June 18, 2025

Today, I'm offering you an article about pants and any garment with a crotch. As we all know, it's never easy to get the crotch perfectly draped when you start sewing pants or shorts. It's a real headache and it's enough to make you want to tear your hair out!

There are indeed a multitude of body shapes and postures. All these possibilities make it impossible to design a garment with a crotch that will suit all body shapes (exit oversize cuts which obviously have the advantage of adapting better to all body shapes!).

Here, I offer you an article allowing you to make 7 common corrections to make to improve the appearance of your pants and shorts!

1. Poor belt alignment

The observation: Folds are created on the front and give a baggy effect, the pants butt up on the buttocks.

The solution: On your front, you will pin the excess at the waistband, creating a dart along the waistband. The value found will be transferred to your trouser front pattern. You will then be able to trace your waistline. If your trousers are too tight in the back, you will transfer this value to the middle of the back to add some back height. I advise you to modify the front, see how it looks before starting a modification to the back (especially if you feel comfortable with the back).

2. The pleat under the belt at the back

The observation: A crease forms in the back under the waistband. The pants don't flatten because there is excess material.

The solution: To make the pants fit better, pin a pleat under the back waistband to make the creases disappear. The value found will be transferred to your back pants pattern. You will then be able to trace your waistline while maintaining a right angle with the back crotch line.

3. The crushed buttock

The observation: The buttocks are bulging and the pants are pulling at the back. The buttocks are compressed and it's not comfortable.

The solution: Looking from the side, you will notice that your side line is oriented towards the back. at the level of the large hips. You will need to estimate the missing value (you can use a string with a weight on the end to align it with your side line at the waist and leave it weighted, the gap will be measured between this string and your side line). You will then need to open your back leg pattern in two at the level of the straight grain normally positioned in the middle of the back leg, if this is not the case position it correctly). You will also cut it perpendicularly at the level of the large hips (you will thus obtain 4 pieces). You will then need to distribute your side offset value on either side of the straight grain and reposition each piece as in the diagram below. The side line will need to be redrawn as well as the back crotch and the inner leg assembly line. Your waist will also need to be redrawn a little, taking care to keep the initial measurement of it.

4. The fork is too low

The observation: The crotch of the pants is too low and does not match the rendering of the model. It gapes and is not to your taste.

The solution: You will measure the front and back of the fold formed by the excess at the level of your crotch. You will then simply raise the front and back crotches by this amount.

5. The fork that goes in the wrong place

The observation: The crotch of the pants is too high, it goes in at the front and back and it's unpleasant.

The solution: You will need to estimate the missing value (usually you will have to go down between 1 cm and 2.5 cm maximum). You will then simply need to lower the front and back forks by this value.

6. The front fork is too tight

The observation: Wrinkles form and whiskers appear as soon as the pants are put on. The pants are too small at this point.

The solution: You will add fork width to the front only. Be careful not to shift the waist.

7. The crotch at the back is too inward

The observation: The back fork goes into the bottom of the buttocks.

The solution: You can shift the tip of the back crotch by 1 to 2.5 cm (depending on your body shape and your needs). I advise you to go there in stages.