A question regarding how much backing and batting to buy
 

I just finished a lap quilt that measures 57wx70L. What size batting can I get away with and do you think 3-4 yards of backing will finish this quilt?

Money is super tight right now so I don't want to waste anything in getting more then is actually needed but for the life of me and after looking at charts, I can't figure this out. I guess you could call it being in a brain freeze and I need help.

My quilting calculator tells me that you should need 3 1/2 yards to 4 1/8 yards depending on which way you run the backing, so you might to able to make it. If you're a little short, you can always just add a strip of a coordinating fabric. Batting can be pieced with a zigzag stitch, so you might be able to use up some smaller pieces if you have them.

You need a minimum of 2" more on all 4 sides so your batting and backing should measure at least 61" x 74". If you are buying prepackaged batting, a twin size would do. If buying batting by the yard, 2 yards of 90" wide batting will be more than enough. I find that wide quilt backing fabrics or wide muslin is less expensive than regular 42" wide cottons. If you buy a wide fabric backing, 2 yards will be more than enough. I like to use old sheets for backs if I can find one in the right color, do you have a Goodwill or other Thrift Shop close to go find a sheet for a couple of dollars for the back??

I use the free Robert Kaufman app on my android phone or Ipad for backing, batting, borders and binding. It is the best thing next to sliced bread!

If money is tight, I usually pieced down the center using scraps so I only by the length that is needed. Batting if you are buying by the yard is usually 90" wide so just buy your width of your quilt.

I'd look for a new cotton sheet. Flat sheets can often be purchased for less than $15 in my part of Canada. In spite of what some quilters think, sheets do make excellent backs and are a lot cheaper than quilting fabric.

It all depends if you are sending It to a LAQ or mot. Most LAQs have batting and they require a certain extra length and width to the backing. If you are quilting it yourself 3 inches all around should do for the batting and backing.

Exactly... I rent a LA to quilt my own but I still add 3 to 4 inches on each side so that it loads easily. When I used to send them to be quilted I believe they required even more than that. Besides a zig zag to join batting pieces, there is also a fusible tape that works well too.

Bet you have large pieces of batting left over from previous projects as well as a stash of fabrics including leftover pieces. They can be pieced into larger sizes as needed. The backings can look really sharp, like having another quilt on the back.

When hand quilting and using glue basting, it is not necessary to have so much excess backing and batting.