How much pressure should be in my pressure tank?

Pressure tank on what, boiler or water heater? Also are you on city water or well water?

My well water pressure tank

my well water pressure tank

I assume you have a bladder tank. Your air setting on the tank should be 2 pounds UNDER the cut in point in the pressure control box. If your pressure control has a 20 PSI cut in and 40 PSI cut out the tank pressure should read 18 PSI. The bladder tank setting MUST be made with the pump off and the system bled down by opening a cold water faucet after you shut the system down at the breaker box. Hope this helps and thank you for rating my reply. Tom