The calculator is built assuming zero bracing with a safety factor of 3.8. A lower safety factor has been shown with many commercially built aquariums. My best advice is to plug in known configurations suchs as a 55 gallon tank and see what safety factor they truly hold. Once you are comfortable with the numbers and the style of tank you wish to build you can use it to test your dimensions/build with what you are comfortable with. This is why I made the caluclator tweakable. It can reverse calculations for both glass and acrylic