Checking an SSD’s health takes one free download and two minutes — and this guide covers exactly how, on Windows and Mac. It also covers the part vendors soft-pedal: the number on the screen measures wear, and wear is not what kills most SSDs.
Health percentage tracks how much write endurance the flash has left — a slow, predictable decline. Real-world SSD deaths are mostly sudden controller and firmware failures the gauge never sees coming.
On Windows, CrystalDiskInfo reads SATA and NVMe drives alike and puts the health percentage and temperature front and centre. The manufacturers’ own tools go a layer deeper for their drives — Samsung Magician, Crucial Storage Executive, WD Dashboard — adding total bytes written and firmware update checks. On a Mac, Disk Utility gives the one-word SMART verdict, and smartctl from smartmontools prints the full NVMe health log, Apple silicon included. Whichever tool, you’re reading the same self-reported ledger.
Four lines are worth your attention. Percentage Used (NVMe’s wear counter — 0% is factory-fresh) or its mirror-image ‘health’ score. Data Written against the drive’s rated endurance (the TBW figure on its spec sheet) — most people are startled how little of it they’ve spent. Available Spare — the reserve of replacement flash blocks; healthy drives sit at or near 100%, and a falling spare is the flash-wear equivalent of reallocated sectors on a hard drive. Media and Data Integrity Errors — should read zero, and any climb means the flash or controller is misbehaving now, whatever the headline percentage claims.
A hard drive usually fails like an engine: noises, slowdowns, warning lights, then the breakdown. An SSD fails like a lightbulb. The controller chip that orchestrates everything, or the firmware it runs, hits a fault — and a drive that scored 98% on Tuesday is absent from the BIOS on Wednesday. No SMART attribute predicted it, because the component that failed is the one doing the reporting. Two consequences follow. First, a good health score is never a substitute for a backup — if anything, SSDs’ silence before failure makes backups more critical, not less. Second, sudden disappearance usually isn’t data death: behind the failed controller, the NAND flash chips typically still hold everything, and SSD not detected recovery — firmware repair, or reading the chips directly and reassembling what the controller scrambled — is precisely that job.
One quiet SSD-specific behaviour worth knowing: TRIM. Modern systems tell an SSD to erase deleted files’ blocks within moments, permanently — so ‘undelete’ software that works wonders on hard drives and cards mostly comes back empty on an internal SSD. On these drives, the backup is the recovery plan for deletions.
Everything zero, spare at 100%: note the Data Written figure somewhere and re-check twice a year — that’s the whole regime. Spare falling, media errors appearing, or the drive stuttering with system freezes: that’s amber — copy your files off now while it reads, then replace it; don’t spend the drive’s remaining goodwill on benchmark passes and vendor ‘repair’ scans. Vanished, wrong capacity, or locked read-only: the controller has had its event. Stop power-cycling, skip the firmware-update roulette, and get it to a bench — our SSD & NVMe recovery service exists for exactly this ending.
The health check earns its keep hardest at the moment of purchase. Buying a used laptop or a second-hand drive? Run the reading before money changes hands, or within the return window: total data written against the model’s TBW rating tells you whether you’re buying a lightly-used drive or one that spent three years as a mining scratch disk — identical from the outside, thousands of terabytes apart inside. Sellers rarely object to a two-minute CrystalDiskInfo glance, and an objection is itself an answer. The same pre-flight applies to ‘refurbished’ drives: a reset operating system doesn’t reset the wear ledger, which is exactly why the ledger is the thing to read.
Read it as fuel remaining, not as safety. The percentage tracks how much of the flash memory’s rated write endurance is left — 90% means you’ve used a tenth of the wear budget. Most SSDs retire from computers with the vast majority of it unused. What the percentage doesn’t track is the failure that actually takes SSDs out: the controller, which can die at 99% health without notice.
In write-endurance terms, longer than almost anyone uses them — typical drives are rated for hundreds of terabytes written, which is many years of ordinary use. In practice, SSDs fail the way electronics fail: a controller or firmware fault, often sudden, sometimes in year two, sometimes in year ten. That’s why the honest answer is ‘until it doesn’t’ — and why backups matter more with SSDs, not less.
Frequently not, and this is the most misunderstood SSD failure. A dead controller or corrupted firmware makes the drive vanish from the computer while the flash chips behind it still hold everything. The data is intact but unreachable by normal means — reaching it is chip-level and firmware-level lab work, not software work. What matters at your end: stop power-cycling it in hope, and don’t update or reflash anything.
Same idea, different dialects. NVMe drives report a standardised set — Percentage Used counting up, Available Spare counting down, media-error tallies — so any tool reads any brand consistently. SATA drives speak older SMART, where attribute numbering varies by maker and the ‘health’ score is the tool’s interpretation. Practical upshot: on SATA, trust the maker’s own dashboard for the friendliest translation; on NVMe, the numbers mean the same thing everywhere.
Free diagnostic at our Belfast lab — controller, firmware and chip-level SSD work quoted in writing before anything begins, with no fix, no fee on most jobs.