Candidate drive test
SSD Endurance & Lifespan Calculator
Test rated TBW against measured or planned host writes with low, base, and high WAF scenarios.
Endurance outlook
| Scenario | Years to rating | Required TBW | Margin |
|---|
Decision guide
Turn a write workload into an endurance planning scenario
What this tool helps you decide
This calculator answers whether a specific SSD rating leaves adequate write headroom for a stated planning horizon. It separates the drive capacity, TBW rating, current host-write counter, daily logical workload, and a chosen WAF scenario. The decision is not “will this drive fail?” It is whether the warranty-style endurance allowance appears proportionate to a workload you can describe. Low, base, and high cases make uncertainty visible instead of hiding it in one supposedly typical multiplier.
Before you start
Gather the capacity, TBW or PBW rating, warranty years, and existing host writes from a current device or specification sheet. Estimate a normal daily logical write rate from monitoring over enough days to include busy periods. Pick WAF scenarios that your team can explain; they are planning assumptions, not certified values. Enter a reserve for uncertainty or a desired early-replacement buffer. A zero write rate is valid evidence only if measurement actually supports it.
How the calculation works
Effective writes per day equal logical GB per day multiplied by WAF. Required TBW equals effective daily writes times 365 times the planning years, divided by 1,000; the reserve increases that requirement. Remaining TBW is rated TBW minus existing host writes. Years to rating divides remaining TBW by effective annual writes. Rated DWPD uses rated TBW, capacity, and warranty years. Actual workload DWPD uses effective daily writes divided by capacity GB.
How to interpret the results
Pass means the base scenario exceeds the requested need with room; Marginal means it meets the model but leaves little room; Insufficient means the planned requirement is higher than remaining rating. Compare all three scenarios rather than treating the base case as fact. Existing writes reduce remaining allowance immediately. If the rating is already exceeded, stop the forecast and verify the counter and units. The result informs maintenance and procurement planning, not a prediction of physical failure.
Worked example
A 1 TB SSD rated for 600 TBW, with 120 logical GB per day, a base WAF of 1.5, a five-year horizon, and 20% reserve needs 394.2 TBW. With no existing writes, its base margin is about 1.52× and its base endurance duration is about 9.1 years. The low and high WAF rows show why a single lifespan claim would be misleading. Adding 150 TB of observed writes cuts every remaining result.
Assumptions and limitations
TBW is an endurance and warranty-planning metric, not a clock for physical failure. The calculator does not model temperature, controller health, interface errors, power events, wear leveling, firmware behavior, spare area, workload bursts, or manufacturer warranty exclusions. WAF may vary with data pattern and operating conditions. Decimal units are used for the formula. Do not call a scenario guaranteed, manufacturer-certified, or typical unless your evidence independently supports that wording.
Next steps
Convert unfamiliar labels in the TBW & DWPD Converter, then measure counter changes in the Remaining Endurance Planner. For cache or virtual workloads, model per-drive distribution before buying. Keep the result with its WAF, reserve, measurement window, and source documentation so a later review can explain why the replacement budget was chosen.