DIY: How to Alter a Pattern

Whether you need to lengthen or shorten a garment, these DIY instructions will teach you how to alter a pattern.

September 8, 2014

By Amy Barickman

The Magic Pattern Book (Workman Publishing, 2014) by Amy Barickman reveals 6 magic patterns that can be transformed into 216 different looks. Her exciting, surprising and stylish book comes complete with beautiful full color photographs and illustrations, step-by-step instructions and a CD of printable patterns. The following excerpt from “Sewing Basics” shows you how to alter a pattern to fit your needs.

To alter a pattern is to change its structure so that the end garment will fit your particular body. Most pattern sizing is based on a single bust/waist/hip proportion—but not all bodies conform to that proportion!

Often, there are small alterations that need to be done, with concerns toward height or sleeve length. These are easy to fix, since many pattern pieces already have preprinted lines where you can lengthen or shorten your garment. If the pieces you need to lengthen do not have lengthen/shorten lines, add your own! (In order to maintain the original silhouette of the garment, it’s important to adjust the garment from a fairly central location, allowing any pattern pieces that attach to the lower edge of the garment piece to still fit.) The best place to add these lines, generally speaking, is (for a dress, top, vest, cardigan, or coat) about halfway between the bottom of the armhole opening and the hem. For a skirt, add the line about halfway between the crotch and hem, and for a sleeve, add it halfway between the bottom of the armhole opening and the hem.

To Lengthen a Garment

1. Gather all of the pieces you will be altering. Be sure to change the front and back as well as any facings. (It is imperative that they all have the same changes made!)

2. If the pieces you need to lengthen do not have lengthen/shorten lines, add your own. (Remember, add length in the middle, not at the edge, of the pattern piece.) Using a clear ruler with a grid, draw a horizontal line perpendicular to the grainline or fold of the pattern piece all the way across it.

 Lengthen Shorten Line Diagram

3. Cut straight across the pattern piece on the line.

 Cut Apart Diagram

4. Tape a piece of lightweight paper underneath the upper piece that is larger (i.e., wider) than the length you need to add. Line a ruler up with the grainline and draw it onto the added paper. Determine how much length you want to add, and draw a horizontal line marking that length beneath the cut edge of the pattern.

 Altering a Pattern Diagram

5. Align this drawn line with the cut edge of the bottom pattern piece and tape.

 Adding Additional Length Diagram

6. Now, fill in the side edges with your pen or pencil. If the lines are uneven, just use your eye to connect them smoothly. Cut along these drawn lines to remove extra paper at sides.

 Draw Sides and Trim Diagram

To Shorten a Garment

1. Gather all of the pieces you will be altering. Be sure to apply the same alterations to every pattern piece involved: front, back, facings, and so on. If the pattern pieces do not have lengthen/ shorten lines, add them as in Step 2. Remember, subtract length in the middle, not at either edge, of the pattern piece.

 Lengthen Shorten Line Diagram

2. Determine how much shorter you want your garment. For example, if you want to shorten the garment 2", draw a horizontal line with your ruler 2" above your lengthen/shorten line. Fold the pattern back on itself, aligning the grainline, neatly creasing the paper along the new line and lengthen/shorten line.

 Fold Lengthen Shorten Line Diagram

3. Tape the fold in place, if desired. Use a clear ruler to make sure the fold is even all the way across.

 Lengthen Shorten Line Diagram

4. If the outer lines of the pattern are now uneven, use your pen or pencil to draw a new line making a smooth transition across the fold. Cut the pattern paper along the newly drawn line. You have shortened your garment by 2".

How to Adjust Pocket, Button, Snap Placement, and More . . .

Another thing to consider when lengthening or shortening a garment is pocket placement. A pocket placement guide is marked on the pattern pieces, but if you alter the garment’s length, you may wish to move the pocket placement up or down slightly. There may be notations on pattern Front pieces for snaps, buttons, buttonholes, or other closures, and even spacing of these may be affected by altering the length of your garment. If necessary, use your ruler to measure and apply revised placement notations that are equidistant and work with the new length.

When altering your pattern, copy the original pattern piece onto pattern tracing paper, which is available at your local fabric store, or even onto freezer paper, available at a grocery store. (For smaller pieces, even newspaper will suffice.) This way, you will still have the original pattern piece, as well as your altered version. Take notes about the pattern as you sew, which will help you when you go to make it again. Although you are investing a little more time in making a muslin and learning about alterations, in the end it will make future projects sew more smoothly, and your finished projects will look tailored and professional.

Reprinted with permission from The Magic Pattern Book by Amy Barickman and published by Workman Publishing, 2014.

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