dsch

I love making tote bags for my friends; however, I'm having trouble with the linings. The body of the bags are pieced from whatever I have left over or in a variety of larger pieces. The body of the bag is cut 15 1/2" (tall) by 19 1/2" (wide). Then I sew about a 3/8" or 1/2" seam each on the bottom and sides, leaving the top open. Lastly, I make the 2 1/2" corners at the bottom.

If I cut the lining from a single fabric, how big should it be? 15 1/2" x 19 1/2" is too big and doesn't fit smoothly. Is there some formula that will help me make my bags? I also make smaller bags for my grandkids and some kind of formula would be helpful for that also.

If X is the width of the outer bag and Y is the height of the bag, how much do I make the lining?

Thanks so much for your help!