I like wider bindings on my quilts, usually .625", so I cut mine at 3", but I know that's not the norm. Here's the way I learned to figure it for double fold bindings:

1. Take the width you want your finished binding to be (for instance, ½")
2. Multiply that number by two (1") (for front and back)
3. Add ¼" to that number (1 ¼") (for the seam allowance on the front, there is none on the back)
4. Multiply the new number by two (2 ½") (for the folding)

or the quick way:
Multiply the finished width by four and add a half inch for the seam allowance. Works every time! :wink:

I cut mine at 2 1/2"- when I'm done, I unfold the pressed areas and iron it flat. Then it goes to the scrap bin for future use. :)

I'm a 2 1/2" er myself. Some days I can't imagine having one bit less. Perhaps it's like pie crust in the beginning you need a lot to get the job done and as you get better and better you don't need so much? :wink:

If you use 2 1/4" can you machine sew instead of hand sew the back?

I use 2 1/2" also. I find it easier to cut than 2 1/4. And then also I add the extra to the scrap bin