Saw this bag reviewed on Mia's Creations. This is a PDF pattern by Projects by Jane. Since Mia had a coupon for this bag, I thought I would try this designer. I really liked the round bottom and I needed a lunch bag, and thought it would be perfect for my salad container. Bought the pattern and made it. As you see, it was a bit too small.
So I decided to resize it by adjusting the size in the Print option. Jane even has a tutorial on her blog on how to resize the templates. Printer was out of ink, and there was no extra cartridge. So I decided to go back to the old math formula. Since I knew what finished diameter I needed, I just plugged it into this formula (had to google it since I could not remember it)
Circumference = pi multiplied by diameter
The round bottom:
I also like the way casing is made. It's a bit different from other drawstring bags in that the ties are right at the top without a border/ flange.
I used a quilting cotton for the fabric. I interfaced the exterior bottom with a fusible fleece and the lining bottom with a medium weight woven fusible called Presto. The only problem I had was when sewing the bottom, there were puckers, so I resewed it at 1/4 inch (6mm) seam allowance instead of the 3/8 inch.