Memory controller and operating method thereof

A memory controller for controlling a memory device including a plurality of memory blocks, the memory controller comprising:

• a remaining count determiner configured to determine a remaining count that is a number of program and erase operations to be additionally performed in the memory device based on a program/erase count received from the memory device;
• a retention period calculator configured to determine a retention period based on a power-off time and a power-on time of the memory device;
• and
• a read voltage determiner configured to generate a changed read voltage table based on a default read voltage table and a coefficient determined according to the remaining count, and determine a read voltage to be used in the memory device, according to the retention period, from among read voltages included in the changed read voltage table,
• wherein the read voltage determiner generates the changed read voltage table by multiplying read voltages included in the default read voltage table by the coefficient.