Calibration instructions: 1. Remove input power then press left button.Then connect input voltage.if display flashes then release left button.Measuring output voltage by multimeter and adjust right/left buttons to set output voltage around 5V such as 4.98V~5.02V.Do not care about the LCD display voltage during set. Link Video : https://www.youtube.com/watch?v=6mw3UMB5e3o