What is Seam Line Ease?


Most sewers are pretty familiar with the term “easing”. You’ll find it in almost all pattern assembly instructions and you’ve probably done it several times if you’ve been sewing for any length of time at all. If you're new or returning to sewing you might be wondering what it is, when you might use it and why it’s even there, so let me clear all of that up for you.

Let’s start with a definition. In essence easing is a sewing technique used to compress a longer seam line length into a shorter one without creating pleats or gathers. There are a few techniques you can use to achieve this but before we get to that I want to explain why the technique even exists.

Simply put, easing adds 3-dimensional shape and replaces darts. As a result, you’ll find that you’ll often be directed to ease is some very specific areas of the pattern.

For Example:

  • Easing in the back shoulder seam or back neckline will replace a back shoulder dart.
  • Easing at the back underarm seam of a sleeve replaces an elbow dart.
  • Easing at the front side seam of a t-shirt replaces a bust dart.
  • Easing in the front side panel of a princess seam creates additional shaping for the side of the bust.
  • Easing in the sleeve head adds shape to the cap of the sleeve.

These are just a few examples of where you’ll find seam line ease but they are good examples of "easing" in use, so if you’re ever wondering why you might need to ease in a specific seam line, simply ask yourself, what body contour is this seam trying to address?

Body contours, or the body’s hills and valleys as I’ve described before, require darts to create shape. When the shaping required is small, easing is a good alternative to darts. So that brings me to a question I just know you’re about to ask, how much length can you successfully ease into a seam?

Well, it depends. It depends on how long the area of easing is. For instance, in a back shoulder seam you’ll find that ¼” (0.6 cm) is pretty standard, but depending on your fabric you can sometimes manage up to ½” (1.3 cm) depending on the overall seam line length and the fabric you’re using. In a front side seam you may be able to manage between 5/8” to 1” (1.5-2.5 cm) because that easing area is generally longer. The deciding factor of how much you can realistically ease in is whether or not you can manage the easing without creating pleats or gathers.

Ok, so let’s sum up with a few easing tips.

My first tip is to baste the longer seam line and draw it in to match the length of the shorter seam line. This is the method I use. I usually machine baste 1/8” narrower than the seam allowance so that when I stitch the seam it is clear of the basting stitch and I can easily pull out the basting stitch when I’m done.

My second tip is to put the longer seam line length on the bottom next to the machine’s feed dogs and my left hand between the two layers of fabric. The action of the feed dogs will naturally draw in the longer seam line length and I can help the machine along by feeding the extra length in with my hand.

If you have your own tips you’d like to share, please add them below.

Next week, I’m going to share a pattern-truing tip that you rarely find in books. I hope you’ll tune in.