I want to adapt a pair of pants to add elastic to the waistband. I have a particular "stretchiness" in mind for this project, but don't know how that relates to a given thickness, width, material, or other characteristic of any particular elastic product.

Is there any standardized terminology for relative stretchiness that I could use when talking to a sales assistant? Are there better ways to choose what elastic to use for a project than standing in the store and pulling on samples to guess how well they would work?

I'm looking for general advice rather than "here's what's best for your pants" -- because this does come up in multiple projects :)

2 Answers 2


This is commonly called the "stretch percentage" or "stretch factor". The name comes from how much percent of the original width/length the material can stretch. For example, if you can stretch a 4" piece of elastic to 6" long, the stretch percentage would be 50%.

Here's a simple visualization from Patterns for Pirates:

Stretch percentage diagram

As a side note, some patterns come with a "stretch gauge", instead of telling you a stretch percentage. It's usually printed on the back of the envelope so you can easily measure your fabric against it:

Stretch gauge example

What elastic to use really depends on your particular application! A thicker or wider elastic may be more sturdy but less comfortable, for instance. As a general rule, thicker elastics seem to be less stretchy - but it's a very general rule. If you know the measurements you want for the finished pants, you can come up with the required stretch percentage: (fabric width / fitted width - 1) and bring that gauge to the store to find which ones are suitably stretchy.


Typically you choose the width of the elastic based on the width of your waistband. So if you have a 1" wide waistband, you'll need 3/4" to 1" wide elastic. You control the stretch by using more or less elastic. If you're sensitive to tight waistbands, then just use a longer piece of elastic.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .