According to an embodiment of the disclosure, a video decoding method includes obtaining, from a bitstream, information indicating a first difference between a maximum size of a coding unit of which a width and a height have a ratio of 1:4 and a size of a largest coding unit, determining the maximum size of the coding unit of which the width and the height have a ratio of 1:4 by using the size of the largest coding unit and the first difference, determining a minimum size of the coding unit of which the width and the height have a ratio of 1:4 based on a minimum size of a coding unit, determining whether it is possible to generate a coding unit of which a width and a height have a ratio of 1:4 by splitting a first coding unit based on the maximum size and the minimum size of the coding unit of which the width and the height have a ratio of 1:4, and determining a second coding unit including the coding unit of which the width and the height have a ratio of 1:4, from the first coding unit, and decoding the second coding unit.