On the kid size quilts I have been making for about three years I have been good at guessing how much binding I need. I seldom have to add unless it is a larger kid size. I usually/almost always need 6 WOF strips with diagonal piecing. No math needed.

I would add the outside circumference (the length around the outside of the quilt) and cut that many inches from the width of fabric, adding 2.5 inches for each strip and one more 2.5 inch for the join. Yes, 2.5 is all you need for the join; you cut off the overlap at 2.5 inches. So the circumference is 322 inches. The usable fabric is 40 inches wide. 322 divided by 40 is 8.05 strips. So you add 8 times 2.5 plus one more 2.5 for all the joining seams and you get 22.5. Nine strips will be plenty. Nine times 2.5 is 22.5 inches. Add a little for squaring up the fabric and 24 inches should do it.

If you make your binding another width, substitute that width in the above formula.

I don't measure inches. I measure the number of strips I need to cut.

The width of fabric is 40-42". Using 40", two strips would give you 80". That's enough for the 68", but not for the 93". I would cut 9 strips: 2 each for the top and bottom, 2-1/2 each for the sides. For fabric requirements, 9 strips at 2-1/2" means you need 22.5 inches.

Thanks, Trisher! Have the Robt Kaufman one for mobile devices, but wanted a simple one for the pc. Now I have one!

Remember that you will have to allow for seam allowances for all the joins.

I would rather cut too much binding than be 1/2 inch short.

So Glad I joined Quilting Board, I will be learning a lot from you experts. :)

I just went through this exercise yesterday. I generally only figure on 40" for the width of fabric and I add at least 10" for overlap at the end as a fudge factor.

This is the way I determine how much I need also.

I always cut my binding longer than I need....I would so much rather "cut off" than have to "add on"...My way is not scientific at all...I take the side and end measurements...double them..than add 4 or 5 inches.