Memory devices include control logic configured to set a first start program voltage and a first stop program voltage, to load actual first data for cells to be programmed to a level greater than or equal to a first level, and to load inhibit data for cells to be programmed to a level less than a second level. After programming the cells to be programmed to the level greater than or equal to the first level, the control logic is further configured to set a second start program voltage and a second stop program voltage, to load inhibit data for the cells programmed to the level greater than or equal to the first level, and to load actual second data for the cells to be programmed to the level less than the second level, wherein the first level is one level higher than the second level.