I’ve worked as a tailor and patternmaker for film and television for more than 25 years. During that time, I have altered many men’s and women’s suit jackets and developed techniques for making common fitting alterations as efficiently as possible. One of my favorites is what I call the dart-and-drop technique; I’ve turned to it on many occasions.

A dart removes excess circumference

This adjustment solves a common fit issue: the need to take a jacket in through the body. The most obvious approach is to reduce the circumference at the side seams. However, this isn’t always feasible: Many suit jackets have a side panel, which places seams at the side front and side back rather than down the side of the body. A jacket’s side-front seams are not easily alterable because the seam usually runs into a pocket. Plus, there’s often interfacing or canvas structure attached to the jacket front. You could take in the jacket at the side-back seams but, if you pin in these seams and look at the jacket from the front, you’ll see it looks as if it’s floating away from the body.

If you were to correct this fitting problem in the flat pattern, you would do so within the side panel, where a side seam would sit. A reduction there balances the garment. My solution is to take the jacket in at the sides by stitching a dart where a side seam would be. The dart begins at the armhole seamline and travels 3 inches to 4 inches down the jacket, effectively and unobtrusively removing width, from the armhole to just above the waist.

 

The dropped armhole fits the sleeve

To make the dart adjustment, you need to partially detach the sleeves. Once the side dart…