Penny Heron wrote in her great blog post on t-shirt quilts...
As a rule of thumb, twenty T-Shirts are needed for a twin sized quilt; thirty will make a double or a queen. But, remember, you may want to use the front AND back of some shirts. You may even want to incorporate small designs on pockets and sleeves into your finished quilt. These often work well as corner posts in the borders and sashings or as quilt labels.
This is not the time to turn into Martha Stewart! The shirts that are the most worn and stained are their favorite shirts and HAVE to be included in the quilt top. If they are in pristine condition, they never liked them - and there are no memories attached to them. When the shirts are stabilized, even a hole or two won’t matter!
Once you have all the well-loved shirts collected all you really need to do is stabalize the stretch in the t-shirt using a fusible stabilizer such as Easy-Knit and assemble the top.
Eleanor Burns, that old pro, has an easy to follow pattern to use if you would like it we have it in the shop...click here
Want to see some samples...try these sites: