That calculator works for me. I'm 5'9", 160lb, using AL80, wearing 3mm which is by now it's more like 1mm, after 11years, 550+ dives in mostly salt water. I'm using 12lbs for the last 8 yrs. I was as high as 16 lbs in the beginning and slowly drop to 12 lbs as the wetsuit get compressed & becoming more relax in my breathing (less buoyancy of the lung).
The limiting factor of my dive used to be the capacity of the tank. As I gain experience & become more relax & comfortable with the dive & surrounding, the limiting factor is now moved to the bottom time, no longer how much air left over in the tank.