How to Adapt a Purchased Pattern

What you take from this lesson: Make safe modifications to a catalog pattern without ruining the fit.

The rule you can't break

You can modify almost anything on a pattern, with one condition: if you change the length of an edge, you have to change the edge of the piece that is sewn to it by the same amount.

Everything that goes wrong when modifying a pattern comes from breaking that rule. You lengthen the side of the front, forget the back, and when you sew, one side has extra fabric.

Changing the length (the easiest)

Lengthening or shortening the body, the sleeve or the leg is the safest modification. You do it by cutting the pattern along a horizontal line in the straight section—never across a curve—and spreading the pieces apart or overlapping them as needed.

On the body, the line goes between the armhole and the waist. On the sleeve, between the elbow and the cuff. On pants, above the knee. Cutting across the armhole or the rise distorts the curve and ruins the fit.

Changing the ease

To widen or narrow the body, you add or remove fabric at the sides, splitting it between the front and the back. Because the pattern usually covers half of the body, every 1 cm you add at the side adds 4 cm of circumference to the finished garment.

Important: modifying the side changes the length of the armhole. If the change is large, you also have to adjust the sleeve cap.

Changing the neckline

Lowering or widening the neckline is easy to draw and easy to ruin. Two things to watch: the front neckline and the back neckline must still meet at the shoulder, and if the length of the neckline edge changes, you have to recalculate the length of the neckband.

A neckband in stretch fabric is cut shorter than the neckline on purpose, so that it sits snugly. You need to keep that proportion when you modify it.

What is better left alone

The armhole curve and the sleeve cap are the two areas where a modification done by eye costs you dearly. They are calculated so that their lengths correspond, with just the right amount of easing.

If you need to change those, it is no longer an adaptation: it is better to start from a different pattern, or to ask for custom pattern development.

The license allows modifications

Moldey patterns can be modified freely to adapt them to what you are going to produce. The only thing that doesn't change is the restriction on the file: neither the original nor the modified version can be resold or shared.

Common mistakes

• Lengthening one piece and forgetting the piece that is sewn to it.
• Cutting the pattern to lengthen it right across a curve.
• Widening the body without checking that the sleeve still fits into the armhole.

In short

You can lengthen, shorten, widen and change the neckline, always adjusting the piece that is sewn to the modified edge as well. It is best to leave the armhole and the sleeve cap alone.