Hi. I was wondering how to calculate I and W for rectangular and quadratic tubes. I have formulars for massive rectangular and square sections and for circular tubes. I tried to make a formular for a square tube section, based on how the formular for the circular tube looks - but I didn't get the correct result (compared with results from "Sectionananalyzer"). I am calculating som wood box columns, and it would be nice to write the formular - even directly in my Excel calculation sheet, rather than using section analyzer.