Here is the formula for calculating pressure based on the value reading from 4-20mA pressure transducer:

pressure = (current_reading - 4mA) * max_pressure / 16mA

where 
  • max_pressure is the maximum pressure the sensor is rated to measure, eg. 100 psi, 200 psi
  • current_reading is the current (in mA) value that is reported by Zenseio station 
  • the calculated pressure will be in the same units as the max_pressure.