In contrast to SLC NAND, multilevel cell (MLC) NAND stores two or more bits per memory cell. To determine the state of each bit, a voltage is applied and the resulting current is detected. In an SLC device, only one voltage level is required. If current is detected, then the bit stored is 1; if no current is detected, then the bit is 0. For an MLC device, three different voltage levels are used to determine the state of both bits.

Generally, MLC NAND offers twice the capacity as SLC NAND in the same size device and comes at a significantly lower cost-per-bit. Designers will have to make some trade-offs in terms of performance and reliability (since SLC NAND is about three times as fast as MLC NAND and offers up to 10 times the endurance);