TBW: SSD endurance rating

Every SSD carries a number that sounds like a countdown. It is a warranty limit with a test behind it, and the drive has a fuel gauge you can read yourself.

The short answer

TBW (terabytes written) is the maximum amount of data a host may write to an SSD under the manufacturer's rating conditions [2]. JEDEC's standard JESD218 defines how that rating is established and verified [1][2]. In practice it is a warranty figure: Samsung, for example, covers the stated period or the TBW, whichever comes first [4]. Our assessment: use TBW to compare drives and to size your own write load, but do not read it as the day the drive dies.

How it works

1. The definition. The manufacturer sets an endurance rating: the maximum number of terabytes written by a host, using the workload of the application class, such that the SSD keeps its capacity, meets its error and failure requirements, and retains data when powered off [2]. That rating is called TBW [2].
2. Two classes. JESD218 defines client and enterprise classes. In the revision we read, client means 40 °C for 8 hours a day while powered, then 30 °C retention for one year; enterprise means 55 °C around the clock and 3 months of retention at 40 °C [2]. The catalogue now lists JESD218C.01 (Aug 2026) [1]. We did not read that text, so check it for changes.
3. The workload is standard, yours is not. JESD219 defines the workloads used for the rating [3]. JEDEC notes that write amplification depends on the workload and can change over the drive's life [2]. Your own pattern may stress the flash more or less than the test did.
4. From TBW to a warranty. Samsung's 990 PRO data sheet (Rev. 1.0) lists 600 TBW for 1 TB and 1,200 TBW for 2 TB, with 5 years limited warranty, whichever comes first, and says the endurance results comply with JESD218 [4]. Samsung's warranty page shows the same "period or TBW" scheme for other models [5].
5. The drive reports its own wear. An NVMe drive keeps a SMART/Health log. "Percentage Used" is a vendor-specific estimate of the life used; 100 means the estimated endurance is consumed, which may not mean failure, and the value can exceed 100 [6]. "Data Units Written" counts 512-byte units in thousands, so you multiply by 512,000 to get bytes [6][8].
6. How to read it. smartctl -a prints all SMART information, and for NVMe drives it takes the values from the SMART/Health log [7].

A practical example

Own calculation, decimal units: 600 TBW over a 5-year warranty is 600,000 GB ÷ 1,825 days, about 329 GB written per day. If your PC writes 50 GB per day (an assumption, not a measurement), five years add up to about 91 TB, around 15 % of that rating. Then read the real figure on your drive:

sudo smartctl -a /dev/nvme0
sudo nvme smart-log /dev/nvme0

Note "Data Units Written" today, again in a month, and multiply the difference by 512,000 to get your bytes per month [6][8]. Watch "Percentage Used" as well [6]. Device name /dev/nvme0 is an example. Our inventory (as of 14 to 16 Oct 2026) does not record SSD models or their wear, so we publish no values from our own drives.

Checklist

• Compare TBW per capacity between drives, not the headline number alone [4].
• Check the warranty text for "period or TBW, whichever comes first" [4][5].
• Read the SMART log once a month and note Data Units Written and Percentage Used [6][7].
• Convert Data Units Written by multiplying with 512,000 [6][8].
• Do not treat 100 % as an instant failure, and do not treat 0 % as a guarantee [6].
• Keep backups either way: a TBW rating is about wear, not a promise that nothing else fails (see our entry on the 3-2-1 backup rule).