Difference Between MLC and SLC

MLC and SLC is a form of NAND flash memory that are used in SSDs, USB drivers, and memory cards. MLC (Multi-Level Cell) flash memory is a form of NAND flash memory that can store several bits of data per memory cell. SLC stands for single-level cell, and each cell holds only one bit of information.

Read this article to find out more about MLC and SLC and how they are different from each other.

What is MLC?

MLC stands for multi-level cell, and it stores two or more bits of information per cell. This means that each memory cell might be in one of numerous states, indicating various levels of data. MLC memory is less expensive than SLC memory; however, it is also less reliable and has a shorter lifespan. It is commonly used in consumer-grade electronics such as smartphones, tablets, and laptop computers.

The most common MLC NAND flash memory is the two-bit MLC (2bMLC), which can store two bits of data in each cell. Each cell's charge level represents one of four possible values or states, which correspond to two bits of binary data. To store data, a high voltage is applied to the cell, which injects electrons into it, increasing the cell's charge level and changing its state. A voltage is applied to the cell to read data, and the resulting current is measured to determine the charge level, which in turn determines the recorded value.

Each memory cell in an MLC can store numerous voltage levels, each of which can represent a different binary value. A single memory cell, for example, can store two or three bits of data, representing four or eight different states. To write data to an MLC cell, the controller must apply the voltage that reflects the required data value to the cell. When reading data from an MLC cell, the voltage level stored in the cell is detected, which correlates to the binary value recorded in the cell.

The major advantage of MLC over SLC is better storage density. MLC allows for more data to be stored in the same amount of space, making it more cost-effective for applications requiring high storage capacity, such as consumer-grade devices like laptops and smartphones, as well as data centers. MLC is also more energy-efficient than SLC since it consumes less electricity and generates less heat.

However, MLC has a few disadvantages when compared to SLC. The biggest disadvantage is that it is slower and has a shorter lifespan than SLC. This is due to the fact that storing extra bits per cell requires more accurate voltage control, which can result in a greater error rate, which results in slower write and read speeds and reduced endurance. MLC also has a lesser tolerance for high temperatures, which can accelerate the degradation of cells and shorten the memory's total lifespan.

What is SLC?

SLC (single-level cell) NAND flash memory can only store one bit of data per memory cell. Due to its fast write and read times and great durability, SLC flash memory is commonly used in high-performance and mission-critical applications such as enterprise-grade storage systems, industrial automation, and military-grade equipment.

Each memory cell in SLC can only store two voltage levels, which correspond to the binary values 0 and 1. The controller applies a precise voltage level to the cell that represents the desired data value to write data to an SLC cell. When reading data from an SLC cell, the voltage level stored in the cell is detected, which correlates to the binary value recorded in the cell.

SLC has significant advantages over MLC and other types of flash memory since it saves only one bit of data per cell. One of the primary benefits is that it has faster write and read times than MLC since the controller only needs to detect two voltage levels rather than several levels. This makes SLC excellent for high-performance, low-latency applications like transaction processing and real-time data analysis.

Another advantage of SLC over MLC is its more durable nature. This is because writing data to an SLC cell requires lower voltage levels than an MLC cell, reducing the risk of cell breakdown over time. To extend its lifespan and assure data integrity, SLC uses techniques like wear leveling and error-correcting codes.

SLC has several disadvantages too. The primary disadvantage is that it is more expensive than MLC since it can only store one bit of data per cell, reducing storage density. As a result, SLC is better suited for applications requiring great performance and durability rather than high storage capacity.

Difference between MLC and SLC

The following table highlights the major differences between MLC and SLC −




Storage Density

MLC has a high storage density.

SLC has a low storage density.

Bits per cell

2 or more


Write and Read Times




MLC's durability is low.

SLC durability is high.


Less expensive

High expensive

Suitable Applications


Mission-critical and high-performance


In conclusion, the main difference between MLC and SLC is the number of bits of data that may be stored per memory cell. MLC may store more bits per cell than SLC, resulting in increased storage density but slower write and read times and lesser durability. SLC, on the other hand, can only store one bit per cell, resulting in faster write and read times and more durability at a higher cost.

The decision between MLC and SLC depends on the specific application's performance, reliability, and cost requirements, and both have advantages and disadvantages.

Updated on: 14-Apr-2023


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