Casi

I know that there is a formula but how do I go about making a bag that is a certain size. My DIL wants me to make a bag that the bottom is 10 x 13. I usually use the bow tucks pattern.

PaperPrincess

Here's a link that will help you calculate the boxed corners, but you are still going to have to come up with a height measurement on your own.
Here is a link that will help:. I had a better one, but it looks like the site's been taken down.
http://www.sew4home.com/tips-resourc...ow-box-corners