A display device includes a display panel, a backlight module and a circuit. The display panel includes multiple regions. The back light module includes multiple light emitting units, and each region corresponds to at least one of the light emitting units. The circuit includes a calibration lookup table corresponding to a first light emitting unit. The calibration lookup table records a parameter and multiple duty cycles. The circuit accesses the calibration lookup table and determines an output duty cycle according to the duty cycles. The circuit determines a current value of the first light emitting unit to drive the first light emitting unit according to the output duty cycle and the parameter.