Since PDF sewing patterns are always designed to fit an average type of person, it often happens that you need to alter a pattern to fit your unique body before you even start cutting the fabric. One of the more frequent pattern alteration is adjusting the length.

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Serger Pepper - Lengthening shortening pants pattern

How to decide if you need to lengthen/shorten a pants pattern?

Once you have chosen the right size to sew, usually basing on hips (if sewing pants), check size charts and compare any provided length measurement (like inseam or waist to floor, for example) to the one you measured.

Serger Pepper - shorten lengthen pants pattern - size chart

If they are different, it’s time to do an easy alteration: lengthening or shortening the pants’ leg.

Usually, the patternmaker will have drawn these lines for you, like I did on my Justin Pants drop crotch PDF sewing pattern, coming soon on One Thimble. I will use its pattern pieces to show you today’s tutorial.
If the “lengthen/shorten here” lines are missing, you can add them yourself somewhere in the middle of the thigh, between the crotch and the knee, perpendicular to the grainline and parallel to the hem and floor. Don’t forget to add them in both the front and the back leg pieces!

Serger Pepper - Lengthen shorten pants pattern - 1 lentghen shorten here linesHow to lengthen or shorten a pants pattern: a step-by-step

No matter if you need to shorten or lengthen, don’t forget this previous step before you cut your pattern piece at the “lengthen/shorten here” line:

Draw a perpendicular line crossing it, extending a couple of inches (or more, if shortening a greater amount than this) on each side of the “lengthen/shorten here” line.

This will help you putting together again the pattern piece without skewing it.

Serger Pepper - Lengthening shortening pants pattern - 2 draw the guidelines

Now, you can cut along that line!

Serger Pepper - Lengthening shortening pants pattern - 3 cut the pattern pieces

  1. How to lengthen a pants pattern:

If you need to add length to the pants, put a strip of paper under the top edge of the bottom portion of the leg pattern you’ve just cut and tape them together.

Serger Pepper - Lengthening pants pattern - 4 tape the paper

Extend the perpendicular line on the strip of paper to guide you aligning pieces.

Serger Pepper - Lengthening pants pattern - 5 extend the guidelines

Measure along that line the amount you need to add.

Tape the top of the leg piece of the pattern, making sure the perpendicular guideline it’s seamless and perfectly aligned (check it with a clear ruler, if needed).

Serger Pepper - Lengthening pants pattern - 5 extend the guidelinesThen tape the whole thing together, again!
Serger Pepper - Lengthening pants pattern - 4 tape the paper

  1. How to shorten a pants pattern:

Measure along the perpendicular guideline the amount you need to take out, splitting it in two: half toward the bottom of the pattern, half toward the top one.

Mark each point with a blue dot.

Serger Pepper - Shortening pants pattern - 8 measure the length to take outDraw two lines, both parallel to the “lengthen/shorten here” original line, one at each blue dot’s height.

Cut the pattern pieces at these new lines.Serger Pepper - Shortening pants pattern - 10cut out the exceeding paperAlign the two pattern pieces at the cut, so the guideline is seamless and perfectly aligned (check it with a clear ruler, if needed).

Serger Pepper - Shortening pants pattern - 11b align the guidelines


Final lengthening/shortening step: blending!

Blend the edges of the pattern, taking off from one of the pieces and adding to the other.

Judge it with your eyes: you don’t want to have peaks or valleys in the new pattern silhouette!

Serger Pepper - Lengthening shortening pants pattern - trim and blend

A few random tips on adjusting the length of pants patterns:

  1. Use “lengthen/shorten here” lines on the pattern pieces if you need to add/subtract less than 3″;
  2. Draw another set of “lengthen/shorten here” lines, parallel to the printed ones, approx 3″ higher than the original one and split in two the alteration you need to apply;
  3. Make sure you reflect onto the back piece any change you made onto the front one, double checking the amount is perfectly even;
  4. Make sure you changed the length of any pattern pieces involved (yokes, tabs, side panels and so on);
  5. Never cut away notches, when shortening!
  6. If you heavily alter a pattern in length, consider you might need to check that something else might have gone out of balance: think of foot entry becoming too narrow if lengthening a pattern for a Skinny Minnie, or color blocking lines becoming weird-looking if shortening a pattern too much.

That’s almost everything I could think about lengthening or shortening pants. Would you add anything? I am all ears 🙂