Originally Posted by
CorgiNole
To follow up on the example -
7 strips at 2.5 inches/strip = 17.5 inches for straight grain - so you can get by with 1/2 yard.
7 strips at 2.25 inches/strip = 15.75 for straight grain - so you can breath easily with 1/2 yard.
I'm not sure how to translate to bias cut strips for the same amount of binding as so far I've only done bindings using straight grain.
I have a book on drafting quilts which is helpful in determining fabric amounts, and my favorite is Harriet Hargrave & Carrie Hargrave's books - Quilter's Academy series as they walk you through calculating fabric amounts.
Cheers, K
if you are interested in bias bindings, and you should be, they're stronger...then just use what you buy for straight of grain...there are more 1/4" seams in bias, but the square inches needed for binding any size are exactly the same...you will just have more pieces to sew together before you begin...once you put on a double chanel bias binding, you won't go back...they always lay flat and have a double layer and the bias will allow you to work in all the folded edge as flat as can be. it also allows you to round the corners off and go round with the bias with no mitering. but of course, if you do miter, they lay beautifully. the only reason i would use a bit more material than you have figured here is that i use 3.5" to end up with double layer 1/2" bindings.
2length + 2width = perimiter
WOF/3.5" = 10 strips = 400" (using 40 as WOF)
you will have 400 running inches at 3.5
WOF/2.5" = 14 strips = 576" (using 40 as WOF)
you will have 576 running inches at 2.5
this will only be different when cut on the bias because you will have more seams...but they will all be on the bias and lay flat and allow the rest of the binding to lay flat too. so multiply on the straight to find out how much you will get but cut on the bias.
PS..the reason bias binding is stronger is that many threads go over the folded edge as you apply it, because of the 45 deg angle. With straight of grain binding, only one thread follows the edge and when that edge wears, the one thread starts to go and very soon, you have a slit running the length of your quilt with all the raw edges inside. I'm sure you have all seen this on old quilts. I promise, if you need 'X' amount of inches to bind anything, it is the same inches on the bias.