The standard medium size is 10 inches wide and 10 inches tall. The standard size allows you to make smaller widths without the need for a narrower width size, and the 10-inch width is best for large-size kilns.
You will need to add 4 inches to the overall glass size. This extra 4 inches will be the drop portion that will make the base for your free-standing art. Please see our FAQS page for more information.