Width for Quilt Backing
 

When you make a quilt backing, do you make it 3 to 4 inches greater than the quilt top? I so hate to waste fabric and I cut mine only 1 1/2 to 2 inches larger and don't have a problem. I do starch the heck out of the backing so maybe that's why I don't "lose" any fabric as I quilt?

If you quilt it yourself and you are happy with the results, then continue as you have been doing. When I did mine on a domestic machine, I usually went with the same amount as you. I didn't use quite as much starch as you mention. The extra fabric gives you something to hold on to when the quilting gets close to the edge.
If you take it to a long arm quilter, however, they need the additional fabric to attach it to the frame.

I quilt on a longarm, so I try to make the backing 4" wider all around. I don't find it to be a waste of fabric, since after quilting I trim off the extra and use it, usually as binding for the same quilt, sometimes in scrap quilts.

I do the same as Dunster. Extra fabric can also be used for scrappy quilts!

I have quite a bit of scrap batting and sometimes I piece it together for a scrap quilt, linus or animal shelter quilt.

I like to have 3-5" on every side cause what I cut off afterwards can go towards the binding or into my scrap boxes for another project. Anything over an inch is saved.

I always send my quilt tops out and the LA lady always asks for the backing to be 3"-4". When I get it back and trim-I always have scrap fabric for the next quilt so it works for me.

I quilt on a sit-down quilting machine, so I sandwich my own quilts. I don't cut the backing much bigger either, probably the same as you. The only challenge (for me) is keeping it even along the edges when I'm basting.

At least 4" all around since I long arm quilt. The extra is necessary for loading the quilt on the frame. I trim after quilting and use the excess either for binding or for other projects. No waste.