Turning Daily Write Volume Into an SSD Endurance Number
Every consumer SSD ships with an endurance rating, and it is printed in terabytes written — 300 TBW, 600 TBW, 1,200 TBW. Your actual workload, meanwhile, is measured in gigabytes: what a game shader recompile writes, what a video export dumps to the scratch drive, what a nightly backup pushes through. The two only meet once the daily gigabyte figure is restated in terabytes.
That single step is what turns an abstract warranty number into a straight answer about whether the drive will outlive the machine it is in.
TB = GB ÷ 1,000. Worked example: 20 GB of host writes a day is 7,300 GB a year, or 7.3 TB. Against a 600 TBW rating that is 30,000 days of writing — roughly 82 years.The Three Numbers on an Endurance Spec Sheet
TBW — the lifetime budget
DWPD — the same budget per day
Write amplification — the hidden multiplier
Sizing Your Own Write Budget Against the Rating
Enter the gigabytes you write in a year
Multiply your daily write figure by 365 and type the total into the left field, already set to GB. Decimal values are fine and a comma works as the decimal mark just as well as a dot.
Read the terabyte figure and divide into the TBW
The right-hand field gives the annual total in TB the moment you type. Divide the drive's TBW rating by that number and you have the years of writing the warranty covers at your current rate.
Convert what SMART reports back the other way
Monitoring tools often print host writes in gigabytes while the datasheet speaks in terabytes. Type either one in — both fields accept input — and use the copy button to lift the bare number into whatever log or spreadsheet you keep drive health in.
Flip the pair for a budget per day
The swap button reverses the direction so a TBW rating becomes gigabytes, ready to divide by the days in the warranty term. The searchable dropdowns on both sides also reach MB and PB when a tool reports in something else entirely.
How Long a TBW Rating Lasts at Real Write Rates
The table runs the arithmetic across three common consumer ratings. Years are calculated as TBW divided by annual writes, using a 365-day year and counting host writes only — the figure your operating system reports, before any write amplification the controller adds internally.
| Host writes per day | Per year | 300 TBW drive | 600 TBW drive | 1,200 TBW drive |
|---|---|---|---|---|
| 5 GB (light desktop use) | 1.83 TB | 164 years | 329 years | 657 years |
| 10 GB (typical mixed use) | 3.65 TB | 82 years | 164 years | 329 years |
| 20 GB (gaming and updates) | 7.3 TB | 41 years | 82 years | 164 years |
| 50 GB (heavy editing scratch) | 18.25 TB | 16.4 years | 32.9 years | 65.8 years |
| 100 GB (daily large exports) | 36.5 TB | 8.2 years | 16.4 years | 32.9 years |
| 200 GB (constant capture or VM churn) | 73 TB | 4.1 years | 8.2 years | 16.4 years |
| 500 GB (sustained write workload) | 182.5 TB | 1.6 years | 3.3 years | 6.6 years |
The pattern is worth internalising: an ordinary desktop will never come close to exhausting a modern TBW rating, and the drive will be replaced for being small or slow long before it is worn out. Only sustained write workloads — VM hosts, capture drives, aggressive caching — put the top rows of this table in reach.
Matches the units on a datasheet
Endurance specs are quoted in decimal terabytes, exactly the TB this page produces, so the result drops straight into the manufacturer's own figure with no adjustment.
Handles whatever your health tool prints
Searchable unit lists on both sides span bytes to petabytes, so a host-writes figure reported in MB, GB or TB can be normalised without a second calculation.
Clean values for a wear log
The copy button returns the bare number with no unit or separators, which is what a tracking sheet needs if you record host writes every few months to watch the trend.
Rating to daily allowance in one click
Swapping the direction turns a TBW rating into gigabytes, the form you need to work out how much you could write per day and still finish the warranty term inside budget.
Endurance and Wear Questions
Does the warranty end at the TBW figure or at the year limit?
Whichever arrives first. Consumer drives are typically warranted for five years or the rated TBW, so a drive that burns through 600 TB in year two is out of cover even though the calendar says otherwise — and a lightly used drive is out of cover in year six with 95% of its endurance untouched. For nearly every desktop the clock wins comfortably, which is why the table's low rows read in decades.
What does DWPD mean and how does it relate to a TBW number?
They are the same budget expressed differently. Drive writes per day says how many times the full capacity may be overwritten each day for the warranty term; TBW states the lifetime total. Convert with TBW = DWPD × capacity in TB × 365 × warranty years. A 2 TB drive at 0.3 DWPD over five years comes to 1,095 TBW. Consumer drives cluster well below 1 DWPD; datacentre mixed-use models are specified at 1 to 3 because they are expected to be written continuously.
If write amplification exists, is my gigabyte-per-day figure even meaningful?
Yes, because TBW is specified in host writes — the data your system sends — and the manufacturer has already accounted for the controller's internal overhead when setting the number. Amplification still matters for the shape of your workload: long sequential writes stay near a factor of one, while small random writes on a drive kept close to full can multiply the NAND traffic several times and eat the endurance faster than the rating implies. Leaving spare capacity free is the cheapest way to keep it low.
How do I find out how much I have actually written so far?
Read it from the drive itself. SATA SSDs expose a SMART attribute usually named Total_LBAs_Written, in 512-byte sectors — one billion of them is 512 GB. NVMe drives report Data Units Written in units of 512,000 bytes, plus a Percentage Used counter that starts at 0 and passes 100 once the rated endurance is spent. Convert the raw figure to TB, compare it with the TBW on the datasheet, and you have the share of the budget already spent.
Do reads count against the endurance budget?
Not in any way that shows on the rating. Flash wears through program and erase cycles, so an almost read-only drive — a Steam library, a media archive — will sit at the same wear level for years. There is a subtler effect where heavily read blocks can be refreshed internally by the controller, adding a trace of write activity, but it is nowhere near a factor in consumer life expectancy. It is the write column of your workload that decides how the table above applies to you.
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