I have received several inquiries as to how much (length) elastic is needed for the ironing board cover. Since not all ironing boards are the exact same size it is difficult to say.
If you purchase a hank of elastic (packaged bundle) that is more than enough. Just feed the elastic through as instructed in an earlier post and whatever is left over - use for making scrungies or other fun things.
If I were to guess - I would say about 3/4 the circumference of the ironing board over. But that would not be an exact measurement. A lot depends on if you are using an elastic gathering attachment, what settings you are using, what type fabric, etc.
So, like I said there is no way to say for sure how much elastic. In the past I have used the elastic off of a spool of bathing suit elastic that I purchased. I hold it on my lap and feed it and when I am done - just cut off the end.
Hope this helps.