How to adjust pants: flat or strong buttocks

At the level of the buttocks two problems can be encountered: the buttocks are flat or on the contrary they are round. In both cases, discomfort is located at the back of the pants.
But before tackling an adjustment of the pattern, it is recommended to try on a fabric and note the problems encountered. Indeed, the measurement table provided with the pattern does not really allow you to know if such a detailed modification is necessary on a pair of pants.

Basic material to perform a transformation

To transform a pattern, it is advisable to have:

• Adhesive tape

• A parrot rule

• A square

• A graduated ruler

• A support sheet

• A pair of paper scissors

• A fine-tipped pencil/criterion

Definitions

Let's start by defining the term fork : lines drawn on the pants pattern, on the front and back pieces. They correspond to a straight line ending in a pronounced curve.

On the front, the straight line is almost parallel to the straight grain. It is located towards the pubis, where a fly would be. The curved part corresponds to the crotch.

On the back, the straight line is inclined and corresponds to the upper part of the buttocks. The curved part corresponds to the lower part of the buttocks and the crotch.

Round buttocks

Case 1

The belt at the waist goes down and forms a V at the arch. The effect is accentuated in a squatting position.

Extend the back fork height so as to fully encompass the entire height of the buttocks. To determine the amount to add, measure the height of the V formed at the arch.

Case 2

The pants are pulling towards the center seam in the middle of the back. Restore ease in the hollow of the crotch, without touching the waist and crotch points.

Case 3
The buttocks are very rounded and combine the 2 previous cases. Make the 2 modifications simultaneously.

Flat buttocks

The pants are very high at the back, at the waist. A surplus of fabric forms at the hollow of the back. Shorten the height of the back crotch, so as to reposition the waist. To determine the amount to remove, measure the excess fabric forming folds.

Transformation to be carried out

Adjust the fork height

On the back leg, draw an axis perpendicular to the straight grain, halfway between the waist and the hollow part of the crotch.

Cut along the line from the fork, stopping 2-3 mm before the side seam. This uncut part will serve as a fixed point to make a pivot.

Spread the 2 parts of the pants apart to enlarge the crotch or overlap the 2 parts to reduce the crotch.

Trace the fork from the waistline to the hollow of the fork.

Trace the hollow of the fork

Using a ruler, also called a "parrot", trace the curve on the bottom of the fork, adding a few millimeters to the outside of the line.