I am trying to find a formula that will give me engine pressure. And I am actually looking for one that that is kind of a quick and dirty one that is maybe not 100% accurate but will get you in the ball park. Kind of like the 2AM rule in EMS to convert lbs to kg. The one's I have found give you long complex formulas that would take me a week to sit down and work through. What does everyone here use to calculate engine pressure as you are pulling up on scene? I know you can buy fancy calculators that do it for you. I know you can get slide rules etc... but what do you do if you don't have them? You know, when the calculator gets stepped on and the slide rule falls down the storm grate.