Laura created a calculator so that I can plug in the finished dimensions of the bag I want to sew and her calculator will tell me what my fabric dimensions need to be.
Laura's Drawstring Bag With Boxed Bottom Calculator
You will need to cut two pieces of each piece of fabric to these dimensions to create one bag.
In our example we would like our finished bag to be 5"H X 6"W X 4"D
The calculator tells us that for these dimensions, we will need to cut 2 pieces each of main fabric, cotton batting, Insulbrite, and ironing board fabric, measuring 10.5" W X 7.5" H
We will cut out 2" squares from each side of the bottom of the pieces, which will result in a 4" boxed bottom.
We will also need 2 pieces cut from main fabric at 10"H X 2.5" W. These will be folded in 0.25" from each side and sewn down before folded in half the long way for each drawstring casing.
This is not a tutorial for making this bag, this just assumes you already know how to make one and need to customize your sizing. There are many boxed bag tutorials on YouTube. Find one you like and follow it with your customized measurements in hand! Good luck!
Here are pictures of my finished bag for my mini iron: