Buying a used SSD safely
SMART data tells most of the story — check TBW remaining and the Power On Hours before you pay. A drive with 95% life remaining is often a great deal.
1. Read the SMART data first
Before completing a used SSD purchase, ask the seller for a SMART screenshot or run the check yourself if you can test the drive. Key attributes: Media Wear Indicator (NVMe, should be ≥ 90% for a "lightly used" claim), Percentage Used (NVMe, should be ≤ 10%),Power On Hours (context for how long the drive has been running), andReallocated Sector Count / Unsafe Shutdowns (elevated counts are warning signs). Tools: CrystalDiskInfo (Windows), nvme-cli (Linux), Disk Utility (macOS).
2. Calculating remaining useful life
If the drive is rated 600 TBW and the SMART percentage used shows 12%, approximately 528 TBW remain. At your estimated daily write rate (say 30 GB/day = ~11 TB/year), that is 48 years of remaining warranty life. This calculation is obviously optimistic — drives fail for reasons other than NAND wear (controller failure, connection damage, firmware bugs) — but it gives you a baseline.
3. Red flags to watch for
High reallocated sector count or pending sector count: NAND cells being retired — normal in small numbers but concerning above a few hundred. Unsafe shutdown count above 50+ on a consumer drive: suggests power loss events or poor handling. Firmware not updated: some drive models have critical firmware bugs patched in later versions — check the manufacturer's firmware history. Listing claims "barely used" but Power On Hours exceeds 2,000+: that is 83+ days of continuous uptime — not "barely used."
4. Counterfeit and capacity-faked drives
Particularly for high-capacity drives (2 TB+) at low prices, counterfeit firmware can report inflated capacity while the physical NAND is smaller. Files written beyond the real capacity overwrite earlier data. Test with H2testw (Windows) or f3 (Linux/macOS) — these tools write a known pattern across the full reported capacity and verify it. Run this test on any suspiciously cheap high-capacity drive.
5. Warranty status
Many SSD manufacturers offer 5-year warranties transferable to new owners. Check the manufacturer's website with the serial number to verify warranty expiry and whether it is registered to another account. An in-warranty used drive with clean SMART data is relatively low risk. An out-of-warranty drive with high SMART percentage used is a gamble — price accordingly.
Bottom line
Check SMART before committing. Percentage Used (NVMe) or Reallocated Sectors (SATA) tell most of the story. Run H2testw on any high-capacity deal. Verify warranty status with the serial number. A 1 TB PCIe 4.0 NVMe at 5–8% used from a first-gen owner is generally safe; a 4 TB QLC drive with "no SMART data available" is not.