TBW stands for Total Bytes Written, is a metric used to estimate the endurance or lifespan of a Solid State Drive (SSD). It is one of the key metrics used to understand the endurance or reliability of an SSD. TBW tells us how much data an SSD can write, after which it will become unreliable for use. Each SSD is rated for different TBW numbers, and this tells about the ability to handle the wear.
This metric is crucial for understanding the durability and operational lifespan of SSDs, especially in environments with high write demands. When an SSD reaches its TBW (Total Bytes Written) limit, it indicates that the NAND flash memory cells have endured a significant number of write cycles and are approaching their wear-out threshold.
While it’s a common belief that reaching TBW might lead to immediate drive failure or switching the SSD to read-only mode to preserve data integrity, it is not entirely true. An SSD can keep working normally even after going beyond its TBW limits. The actual impact varies depending on factors such as the SSD’s firmware, temperature, applications, the efficiency of its wear-leveling algorithm, and the quality of its NAND cells.
In many cases, SSDs continue to operate normally past their TBW rating without immediate data loss, as modern SSDs are designed with over-provisioning and error correction codes (ECC) to manage cell wear and maintain data integrity.
However, surpassing the TBW increases the likelihood of data errors and eventual drive failure over time, making it prudent to monitor the drive’s health and prepare for replacement as it nears or exceeds this limit.
How to check the remaining TBW of your SSD?
SSDs don’t generally have any direct way to check the existing or remaining TBW numbers. However, there is a method that we can follow to do so. Below is how you can do it.
What happens when an SSD surpasses its TBW limit?
Several things can happen once your SSD exhausts its TBW numbers. Let’s understand all of the things.
1. It continues to function normally
Generally, most SSDs would keep doing their job fine without any issues. However, they wouldn’t remain reliable for data storage and retention anymore. It isn’t that an SSD will shut down once the TBW number hits. Some issues, like degraded performance and more heat, can appear.
2. Wear Leveling and Exhaustion
SSDs have extra space for overprovisioning and wear leveling. The SSD might start to use that space, and once all the available memory blocks are faulty, only then can you experience a complete failure.
2. Read-Only Mode
In some cases, when an SSD reaches or exceeds its TBW limit, it may switch to a read-only mode to protect the data currently stored on the drive. This means you can still access and retrieve your data, but you cannot write new data to the drive. For reading also, internal functioning is necessary, and this can result in a sudden failure even during your drive is working in the read-only mode.
3. Increased Error Rates
As the SSD approaches or surpasses its TBW rating, you might experience increased error rates due to the wear on the NAND cells. Modern SSDs have technologies like ECC (Error Correction Code) to manage minor errors, but as the drive wears out, the effectiveness of these technologies can diminish. You can start to see more errors while gaming or in general. BSOD can also arise because of the exhausted drive health.
4. Drive Failure
Eventually, an SSD that has exceeded its TBW limit might fail. This means it would no longer be recognized by the system, making data recovery difficult or impossible without professional help. Normally, an SSD will give you warnings, and you can manually check for bad blocks. But, it is important to keep a data backup once it approaches its TBW limites.
5. Warranty Considerations
Many SSD manufacturers use the TBW value as a benchmark for their warranty. If the SSD reaches its TBW limit within the warranty period, it might be eligible for replacement. However, if the drive exceeds the TBW after the warranty period, the manufacturer is not obligated to replace the drive.
How much TBW do SSDs have?
The TBW (Total Bytes Written) limits of SSDs vary significantly based on their storage capacity, NAND technology, and intended use case. Generally, larger capacity SSDs and expensive drives have higher TBW limits due to the greater number of NAND cells available to distribute writes, enhancing their endurance. You can estimate the remaining TBW here using third-party tools like CrystalDiskInfo.
Big SSD brands like Samsung, WD, Crucial, and Kingston are known for their better TBW, especially in their flagship products. Samsung generally sticks to 600 TBW for 1TB drives and 1200 TBW for 2TB drives.
High-capacity drives, such as 2TB or 4TB SSDs, often feature TBW ratings exceeding 1,200 to 3,200 terabytes. These figures can vary more broadly with the type of NAND used—SLC (Single-Level Cell) being the most durable but most expensive, followed by MLC (Multi-Level Cell), TLC (Triple-Level Cell), and QLC (Quad-Level Cell), with QLC being the least expensive and having the lowest endurance.
How is TBW calculated?
TBW is calculated based on the endurance characteristics of the NAND flash memory used in the SSD, which is influenced by the NAND type (e.g., SLC, MLC, TLC, QLC) and its density. Manufacturers use standardized testing and write patterns to estimate the average P/E cycles the NAND can withstand, and from there, they calculate the TBW, DWPD, and MTBF figures.
For example, if an SSD contains NAND flash that can endure 3,000 P/E cycles and has a total capacity of 1TB (1 Terabyte), the TBW could be roughly estimated as:
TBW = NAND Endurance (P/E Cycles) × Drive Capacity
This means the SSD can handle approximately 3,000TB of data written over its lifespan. However, this is a simplified calculation. In practice, manufacturers use more complex models that account for wear leveling efficiency, over-provisioning, and other factors.
Effectiveness of TBW Limits in Terms of SSD Reliability
TBW limits are a useful indicator of SSD reliability and longevity, providing a quantifiable measure of how much data can be written to the drive before wear-related issues potentially compromise data integrity.
However, TBW is not the sole determinant of SSD reliability. Factors such as the SSD’s controller quality, firmware efficiency, wear-leveling, operating temperature, and the nature of the workload (e.g., read vs. write ratio, sequential vs. random writes) also significantly impact an SSD’s lifespan and reliability. In real-world usage, SSDs often outlast their TBW ratings without experiencing data loss, thanks to modern SSDs’ sophisticated error correction codes (ECC), wear leveling algorithms, and other reliability-enhancing technologies.
Therefore, while TBW is an important consideration, especially for users with high write demands, it should be considered alongside other SSD specifications and reliability features when assessing the overall durability and suitability of an SSD for a particular application.
How commonly do people surpass their SSD’s TBW limits?
It is very rare for the normal user to surpass even a 300TBW on a 1TB drive. Let’s see which types of workloads can actually have the ability to spend all the TBW.
1. General Users (Web, Office, Light Gaming)
- Writes ~10–50GB/day (~0.5–1.5TB/month).
- A 1TB SSD rated for 600 TBW would take ~30–50 years to exceed TBW.
Example: Writing 20GB/day → 7.3TB/year → 82 years to hit 600TBW.
2. Heavy Users (Possible to Hit TBW)
Content Creators (Video Editing, Large File Workloads)
- Writes 100–500GB/day (~3–15TB/month).
- A 1TB SSD (600 TBW) could hit the limit in 3–5 years.
Gamers (Frequent Game Installs/Updates)
- Modern games (50–100GB updates) add up.
- Heavy gamers might write 5–10TB/month → 5–10 years to hit 600TBW.
Database/Server Use (High Risk of Exceeding TBW)
- Constant logging, VM usage, or caching can write 10–100TB/month.
- Enterprise SSDs (higher TBW) are needed here.
We can say that with consistent heavy workloads, we can surpass the TBW limits, but that, too, in huge timelines. Generally, if your workload is too heavy, you will hardly be able to reach the TBW inside the warranty period. After the warranty period is over, it is, anyway, going to be a risky thing to store your data on your SSD.
I hope this helps.