A modular display apparatus is provided. The modular display apparatus includes a plurality of display apparatuses, each of which includes a plurality of pixels; a storage configured to store a plurality of gain sets, each of which includes gain values respectively corresponding to a plurality of power loads; and a processor configured to: identify a gain set from among the plurality of gain sets based on a resolution of the modular display apparatus; transmit the gain set to the plurality of display apparatuses; receive a plurality of gain values which respectively correspond to power loads for the plurality of display apparatuses to display an image from the plurality of display apparatuses; and transmit a gain value from among the plurality of gain values to the plurality of display apparatuses. Each of the plurality of display apparatuses is configured to display the image by driving a plurality of light-emitting devices of the plurality of pixels based on the gain value received from the processor.