Memory device and operating method thereof

Abstract

There are provided a memory system and an operating method thereof. A memory system includes: a memory device configured to generate first read voltages and second read voltages, based on initial read voltages and first and second offset voltages, in response to a user read command, and output first data and second data, which are acquired by performing read operations on multi-bit memory cells, based on the first read voltages and the second read voltages; and a memory controller configured to output the user read command, wherein the memory controller includes a state counter configured to count numbers of data bits respectively corresponding to a plurality of threshold voltage states from the first data and the second data, and extract numbers of memory cells respectively included in a plurality of threshold voltage regions divided by the first read voltages and the second read voltages by calculating the counted result.