I'm going with losing 1/2" on each join - the 1/4" seam. I intensely dislike cutting extra as I have too many scraps. At least binding ones are useful. I don't work with less than 2 1/2" scraps and I can't find anyone to take my scraps that are from 1 1/2" to 2 1/2". I guess it's time to pitch them.

Oh Irish! Please don't pitch them! There are a lot of Bonnie Hunter fans on the board who would love to take them off your hands, me included!

If it's a print I join straight across. I stopped doing the angle join unless it's a light color solid. One of the best how-to I got from a very expensive quilt finishing lecture at a National Quilter's Association show.

When I figure my binding needs I measure the 4 sides of the quilt, add 10” then divide by 40” to see how many strips I need. If I need 8.25 I cut 9. I figure it’s always better to have a bit extra left over than to run short.

I must have been at that same lecture onebyone. Bias binding joined straight works just fine and the print can be matched to be uninterrupted if that needs to be. I forgot the lecturer but remember she was a national quilt judge that went all over judging shows.

I always make a point of cutting extra strips -- just in case. Extra binding strips are sewn together, pressed in half and wound into coils and stored for later use on another project. This has saved me time on several projects. It just takes a little time to cut more strips while I have the fabric setup to cut them.

Mywebquilter.com is the best free online quilt calculator I have ever found . Has a quilt blocks library ; it's a world of information .

SusiSew, I have an offer posted in that section of the QB for scraps for postage, but have had no responses. I understand because postage has gone up so much.

[QUOTE=Bobbinalong;8299885]For a diagonal join you will lose a little more than the width of your binding strip.
You will also lose a little binding with the mitres on the corners. Quote]

No you don't lose anything on the corners. The edge of the binding lays on the edge of the quilt and just goes around the corner. There is no fold on the exact corner.

The reason for sewing binding on the diagonal is to reduce bulk. If you make seams straight across, you will have 12 thickness of fabric at that spot, plus the quilt top, back and batt. And that's if you pressed the seam open.

But I don't cut my bindings on the 45º either. I lay the strips on the mat, lined up carefully with the printed lines with one inch of overlap. Then I cut an angle from the corner of the top one to the corner of the bottom one. You can't see the bottom one, but the lines on the mat will tell you where that is. That way I only lose one inch instead of the complete width of the binding.

I just make it easier on myself (rather than a bunch of math) and I add 3" per join. So you would have needed 24". I know that is too much, but just easier for the old brain! (i think you used so very little because you were calculating your WOF as 40" and it is often 42" or 43", so you already have some wiggle room.)