Didn't we already have this discussion? I think we did, not that it matters. Bimba, the cylinder manufacturer, gives you the force factor for you. So for this cylinder being 1 1/4" bore it's force factor is 1.2. So if you want 50 pounds of force take 50/1.2 = 42 PSI. That simple. I made a chart for visual reference for these pounds of force 3, 5, 8, 10, 14, 15, 20, 30, 40 and 50. I also took a couple of my scales and put them under the ram and did a real world test the PSIs came out exactly on the button.