How much backing do I need?
 

I'm blank. My quilt is 105" x 105". How many yards of standard width (40-42) fabric do I need for the backing?

I used the Robert Kaufman app: when I enter 42" fabric, 105" width, 105" length and no overage is 8 3/4 yards. If I add 3" overage as usually recommended the yardage increases to 9 1/4 yards. Hope that helps!

Depending on how you put the back together - you could do as little as 9.75 yards - up to 10 yards. You want to go at least 10 inches over to 115 inches x 115 inches. Divide that by 36 inches = 3 ft and 7 in. So I round it up to 3.25 yards.

So if you split your backs - length of fabric you will need about 3.25 yards. x 3 = 9.75 yards
If you sew it width of fabric together I believe you will still need 3 pieces at least 3.25 yards since the quilt is square.

When I find a fabric sale I always buy some with backings in mind. My rule is 2x the length of the quilt. I always have enough using that measure.

That rule would work if your quilt is not wider than approx 80". In this case, the quilt is very large, 105", which is wider than two widths of fabric: 42" wide x 2= 84" would not be wide enough for this one. I have never made a quilt this large, so your rule of thumb would work for me, but not for this one.

Thanks everyone! 10 yards it is...just to be sure. I don't know why I couln't figure that out...glad to ge able to get help from y'all!

I would get 10 yards.. better safe than sorry .... I think I would also see if there is any wide width fabric that would work for the backing. I like using that when possible to save time and sometimes even money

I usually buy from the sale room for backings -- like to look for the 75% off fabric and buy what is on the bolt. I usually get 9 to 10 yards then I'm covered for any size!

If your quilt is going to be wider than 88" you are probably going to need three times the backing fabric rather than two

I use this method of making a large backing:

http://www.reddawn.net/quilt/backings.htm

Good method if your backing doesn't need to be wider than 2 fabric widths. It won't work for this quilt, or for most of the large quilts I make.