Sewnoma

That's what I was thinking! For me, "too much" is often just the right amount, especially when I either decide to change the pattern around (happens a LOT) or I cut the fabric wrong and need to re-do pieces (happens when I'm sick or up too late).

If you're using a purchased pattern it ought to have a list of how much of each fabric to buy to have the quilt finish out at X-size. Some patterns have it for several sizes, some for just one.

If I'm designing my own pattern, what I do is count up and list out how many pieces of each size and in each fabric I'm going to need, and then I figure out how many of that piece I can cut from a strip of fabric cut by the length of fabric. Then I multiply it out to figure out how long of a piece I need to buy.

So let's say my quilt is just a bunch of 4" squares; those are going to be cut at 4.5" square. Let's say I count that I need 30 of them in blue, and my blue fabric is 42" wide after I trim off the selvedges.

42 divided by 4.5 is 9.3, so that means if I cut a strip of fabric 4.5 inches wide by the width of my fabric, that will give me 9 squares per strip with a little scrap left over.

I only need 30 blocks, and if I get 9 blocks per strip, I need four strips and I'll have some blocks left over.

4 strips at 4.5 inches wide is 18 inches. That happens to be exactly 1/2 yard. BUT!! I'm a pre-washer, so after I wash my fabric, trim strings and square up the fabric it's going to be smaller - it'll probably shrink a bit too. Even if you don't pre-wash, if you square up the fabric you're going to lose some, so even though by measurements I only need 1/2 yard, I would buy more to make sure I have enough to handle any wonkiness in the fabric or any sloppy cutting at the store. I would probably go ahead and get 2/3rds yard, which would be 24 inches; that gives me lots of wiggle room.