How to shorten or lengthen a bottom pattern (pants, shorts and overalls)
If when reading the measurement chart attached to the pattern, your height is different from that indicated, then a modification of the leg length should be considered.
Basic material to perform a transformation
To transform a pattern, it is advisable to have:
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Adhesive tape
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A parrot rule
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A square
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A graduated ruler
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A support sheet
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A pair of paper scissors
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A fine-tipped pencil/criterion
Method A : Cut the pattern pieces into 2 or 3 and add/subtract the desired value between the different parts.
Depending on the size of the measurement to be subtracted or added, the pieces will not be modified in the same place. In this way, the lines of the pattern will remain harmonious.
In all cases, method A is recommended so as not to change the cut of the pants.
For more details on this technique, refer to the article entitled "Basic techniques for shortening or lengthening a pattern."
Case of a pair of pants
The measurement difference is less than or equal to 2 cm
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Draw an axis perpendicular to the straight grain on the front and back legs. Place it below the knee line. Mark this line preferably at exactly the same height on the front and back.
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Cut on the line, then spread the pieces apart to lengthen the pattern or overlap the pieces to shorten the pattern.
The measurement difference is more than 2 cm
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Draw 2 axes perpendicular to the straight grain on the front and back legs. Place the first below the knee line and the second above the same line.
Place these lines preferably in exactly the same place on the front and back.
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Cut along the lines, then spread the pieces apart to lengthen the pattern or overlap the pieces to shorten the pattern. Change each axis by half of the total measurement.
Example: Pants need to be lengthened by 5 cm. Add 2.5 cm above the knee line and 2.5 cm below the knee line.
Key point: It is important to check that the knee line is always correctly positioned. Place the paper pattern in front of your leg and visually check that the line is in the right place. Otherwise, distribute the total measurement differently between the 2 axes.
Case of shorts or Bermuda shorts
Since shorts are short by definition, the measurement to be added or subtracted should not be extremely large. It is therefore sufficient to draw a single axis perpendicular to the grain before cutting the pieces and add/subtract the desired measurement.
Place this axis between the crotch point and the bottom line. Preferably mark it at exactly the same height on the front and back.
Example on the Sailor shorts 
Method B : Modify the bottom of the pieces in line with the existing outline.
Depending on the cut of the pattern (straight, flared or tight/hindered) and the desired transformation, it will be possible or not to modify the pieces from the bottom, in the continuity of the already existing outline. It will therefore depend on the case.
For more details on this method, refer to the article entitled "Basic techniques for shortening or lengthening a pattern."
