What is the formula of calculate the tank head pressure? Please tell me

If you mean head pressure above the pump, then you say .43 times feet of elevation. So if your pump is 220' down, it would be 220 x 0.43, or 94.6 psi.

Jliseenbe gave you the formula for calculating head pressure from the bottom of the well up to the surface but that's not what you asked The pressure at your bladder tank id determined by the setting on your control box. If your pump cuts off at 50PSI that's the pressure reading at the tank. Cheers, Tom

A little confusing, Fur. You asked for a formula. Exactly what is it that you need? If you are trying to adjust your system pressure, then SB gave you what you need.