I use 14lbs with my 5mm+hood and 10lbs with my 3mm+hood. The calculator suggested 14lbs and 11lbs. From experience I have to have that weight. I can’t cut even a pound. I’ve tried it. (Actually two pounds because my weights are in 1lb increments and I would have a side to side imbalance.) On some dives I will finish the dive in 10ft or less of fresh water with less than 100psi in my tank. It’s a weird sort of dive but without that weight I have to end the dive because I can’t stay under anymore in such shallow water with so little air in my tank. You should have to have enough weight for a worst case scenario of depth and tank status. You may not often (if ever) run that low on air but it could happen. The calculator is very conservative and seems to work pretty well.