Alot of times the 108" backs are really only about 106". I have a quilt right now to quilt that is 94 X 106, and I have to waste fabric because I'm afraid I will come up short if I lay it out along the 106 side. 110 or even 118 would be nice.

My extra big calif king needed 120 inch wide. Bought it at Joanns.
Washed it and is now 117 and is too small. Had to buy more and cut it down, Im not a happy camper.

As said by someone else 108 or 110 is generally big enough for me.

The shop I work at she keeps off white, white, and tea dye backs in 118-120. All of her other backs are 108".

The quilt top I have on my LA now is 117" square. Since extra fabric is needed all around, the 118" backing still wouldn't be wide enough. But... if a quilt is 110", then 118" would mean not having to piece the backing, so it would be very useful.

That said, if I'm making a scrappy quilt top then I usually piece my backs anyway, using a variety of fabrics. I get rid of large scraps that way, and if the front is scrappy it seems only right that the back should be scrappy too.

I just can not imagine washing, ironing, handling that large of a piece..wow...the weight of it alone would keep most from buying it...

I use 108". When I made my last king size, it even fitted then. The only purpose of this wider fabric is if you want to cut it off and use in another project.

it's great to find 118"-120" wide fabrics- they back king size quilts!
and if your queen size is on the large size- (like with extra over-hang on the sides) the wider might be inportant- especially if you are sending it out to a long-arm quilter- it is important that the backing and batting be larger than the top when being long arm quilted.

When I have a back that big, I DO wash it..but then I load it on the frame. Spray a section with Best press and roll it taut. When it dries, I roll to the next section. VOILA! Nice flat back and NO IRONING! Heaven!

I would imagine that bigger is always better as opposed to smaller. I hate having to piece backings.