A method to calibrate I/O cell current has been described. The method includes setting a global control value provided to the I/O cells. Then, for each I/O cell, the method includes comparing the logic voltage at the output pad of the I/O cell with a reference voltage, and sinking more current at the output pad by enabling additional driver bits associated with the I/O cell if the logic voltage is higher than the reference voltage, or sinking less current at the output pad by disabling additional driver bits associated with the I/O cell if the logic voltage is lower than the reference voltage.