A video decoding method includes obtaining information indicating a first difference between a maximum size of a coding unit having a 1:4 ratio and a size of a largest coding unit, determining the maximum size of the coding unit of having the 1:4 ratio by using the size of the largest coding unit and the first difference, determining a minimum size of the coding unit having the 1:4 ratio based on a minimum size of a coding unit, determining whether a coding having the 1:4 ratio may be generated by splitting a first coding unit based on the maximum size and the minimum size of the coding unit having the 1:4 ratio, and determining a second coding unit including the coding unit having the 1:4 ratio, from the first coding unit, and decoding the second coding unit.