Why do I get drastically different IBU values depending if I enter metric or imperial units? Entered in oz, I get a final IBU of 43. Entered in g, I get 27. I suspect it has to do with the lack of precision. In the recipe editor, the smallest imperial unit increment is 0.1oz. The smallest metric unit increment is 0.1g, which is equal to 0.003oz. That's a difference of two orders of magnitude. It seems to me that if you're using imperial units, don't expect predictable results. I know I can taste the difference between IBU 43 and 27.