SSD Lifespan / TBW Calculator
How much of an SSD's rated write endurance is gone — and what that actually means.
What you provide
Result
PASS6.7% of the rated endurance used
Barely touched. At this rate the rating is not a consideration for this drive — it will be replaced for being too small or too slow long before flash wear is relevant.
- Under half the rating
- Over half — worth knowing what writes
- Past the warranty limit, not past failure
About 42 years to the rating at the drive's own average rate.
- Host writes
- 40.00 TB
- Rated endurance
- 600 TBW
- Rating used
- 6.7%
- Average writesOver the drive's life so far — the best predictor of what it will do next
- 37.4 GB per day
- Years to the ratingAt the current rate, and only to the warranty limit rather than to failure
- 42
What this cannot tell you
- Calculated in your browser from figures you supply. Nothing is uploaded.
- The rating is a warranty limit rather than a failure point. Endurance testing has repeatedly shown consumer drives writing several times their rated figure before anything went wrong, so passing it is not the same as wearing out.
- Projects from the drive's own history, which assumes usage stays similar. A change in what the machine does changes the projection entirely.
- Says nothing about the failures that actually lose data. Controller faults and power loss are sudden, unrelated to wear, and not predicted by any of this.
Take this with you
How this calculation works
You supply the total host writes — from the drive's own SMART data, in terabytes, gigabytes or the 512-byte sectors most tools report — along with the manufacturer's rating and the drive's age. The percentage is a division; the useful part is the projection, which is made from the drive's own history rather than from an assumed workload. A drive that has averaged 15 GB a day for three years is the best available predictor of what it will do next, and that figure is frequently an order of magnitude away from the 20 GB a day endurance ratings are conventionally quoted against.
What the results mean
- TBW
- Terabytes written — the manufacturer's rated endurance, and the point at which the warranty stops covering the flash.
- Rating used
- How much of that budget is spent. Past 100% the drive is out of warranty for wear, not out of life.
- Average writes per day
- Computed from the drive's own history. Compare it with the 20 GB a day ratings are usually quoted against.
- Years to the rating
- At the current rate. For most desktop drives this lands well past the point the machine is replaced.
Common problems and fixes
- My writes look enormous
- Check the unit. SMART attribute 241 counts 512-byte sectors, so the raw number is huge and needs converting — select LBAs above and it is handled.
- The drive is past its rating
- That is the end of the warranty rather than the end of the drive. Confirm the backups and carry on; drives routinely run well past the figure.
- Writes are much higher than I expected
- The usual causes are a swap file on a machine short of memory, a sync client rewriting whole files rather than parts, and logging left at debug level. All three are fixable and none require new hardware.
Frequently asked questions
What happens when an SSD reaches its TBW rating?
Nothing, on the day. TBW is the endurance the manufacturer warrants, not the point at which flash stops working — endurance testing has repeatedly shown consumer drives writing several times their rating before failing. What changes is that wear-related failure is no longer covered, which is an argument for checking your backups rather than for replacing the drive that afternoon.
How much does a normal computer write in a year?
A typical desktop or laptop writes somewhere between 5 and 20 GB a day, so 2 to 7 TB a year. Against a 600 TBW rating that is the better part of a century, which is why wear is rarely what retires a consumer SSD.
Where do I find total host writes?
A web page cannot read SMART data from a drive — the figure comes from a disk utility you run yourself, and every one of them shows it. On ATA drives it is usually attribute 241, counted in 512-byte sectors; NVMe drives report Data Units Written instead, in 512 KB units. Paste that report into the drive interpreters on this site and either format is handled.
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