An organic light emitting display device includes pixels, a sensor configured to extract at least one of deviation information of first transistors of the pixels and deterioration information of OLEDs of the pixels in a sensing period, and a converter configured to change a bit of first data input from the outside by using at least one of the deviation information and the deterioration information, and to generate second data, wherein a pixel at an ith horizontal line includes an OLED, a first transistor configured to control an amount of a current that flows from a first power source via the OLED in response to a voltage of a first node, second and third transistors configured to turn on when a scan signal is supplied to an ith scan line, and a fourth transistor configured to turn on when a control signal is supplied to an ith control line.