CrystalDiskInfo – How to Check Your SSD and HDD Health (2026 Guide)

CrystalDiskInfo is the free little tool that once saved me from losing every photo I owned, and I did not even know I was in danger until I opened it. My PC felt fine. No crashes, no weird noises, nothing. On a whim I ran CrystalDiskInfo to check my drives, and there it was: a yellow “Caution” box on the drive holding years of family pictures. The drive was quietly dying, remapping bad sectors in the background, and Windows had told me nothing. I backed everything up that night. Two weeks later that drive was dead.

That is the whole reason this tool matters. Your hard drive or SSD is the one part of your PC that can fail and take your data with it forever, and it almost never warns you in an obvious way. CrystalDiskInfo reads the hidden health data your drive is already tracking and puts it in plain sight, so you get weeks of warning instead of none. In this guide I will show you how to download and use it, how to read every important number, exactly what Good, Caution, and Bad mean, and what to do the moment you see a warning. I will also be honest about its limits, because a couple of popular assumptions about this tool are flat-out wrong and could cost you your files.

What Is CrystalDiskInfo and How Does It Work?

CrystalDiskInfo is a free, open-source disk health tool for Windows that reads something called S.M.A.R.T. data from your drives. S.M.A.R.T. stands for Self-Monitoring, Analysis and Reporting Technology, and every hard drive and SSD made in the last twenty years has it built in. Your drive is constantly logging its own health behind the scenes, counting errors, tracking temperature, measuring wear. The problem is Windows does not show you any of it. CrystalDiskInfo translates that hidden log into a simple screen anyone can read.

It works on Windows 10 and 11, and it handles traditional hard drives, SATA SSDs, NVMe drives, and many external USB drives. It was created by developer Noriyuki Miyazaki and is available free from the official site at crystalmark.info. The current version as of 2026 is 9.9.2. Because it is genuinely free and open source, you never need to pay for a “premium” disk health tool, those are usually selling you what CrystalDiskInfo already does for nothing.

How to Download and Install CrystalDiskInfo

Getting it running takes about a minute. Go to the official CrystalDiskInfo site at crystalmark.info and download the latest version. Always grab it from the official source rather than a random download site, because disk tools are a common target for fake, malware-laced copies.

You get two choices: the standard installer or the portable version. The portable version is my pick, because it needs no installation, you just unzip it and run it. After downloading, extract the zip, then double-click DiskInfo64.exe on a 64-bit system (or DiskInfo32.exe on 32-bit). You may need to allow administrator rights, which is normal since it reads low-level hardware data. That is it. The moment it opens, it automatically detects every drive Windows can see and shows their health.

If a drive is missing from the list, open the Function menu and choose Rescan, or check that S.M.A.R.T. is enabled in your BIOS. Note that drives inside a USB enclosure, a RAID array, or a NAS often cannot report S.M.A.R.T. data through the bridge, so those may show as unreadable, which is a limitation of the connection, not the tool.

How to Read the CrystalDiskInfo Main Screen

When CrystalDiskInfo opens, the layout is simple once you know where to look. Across the top are tabs, one per drive, each showing the drive name and capacity so you can click between them. The big box in the upper left is the one that matters most: Health Status. This is the tool’s overall verdict on the drive, shown as a colored word, and for most people this single box is all they really need to check.

Right next to it you will usually see a percentage (like 98%) and the current temperature. Below that sits the large table of S.M.A.R.T. attributes, which is where the detailed truth lives if you want to dig deeper. Most people can glance at the colored Health Status box and move on, but understanding the table is what turns you from someone who reads a warning into someone who knows how serious it is.

What Good, Caution, and Bad Actually Mean

CrystalDiskInfo uses a simple color system for Health Status, and knowing exactly what each one means is the whole point of the tool.

The most important honest point in this entire guide: a “Good” status does not guarantee a healthy drive. Good only means no attribute has crossed its manufacturer-set failure threshold yet. A drive can show Good while already having a non-zero reallocated sector count that simply has not hit the threshold. That is why you should not only glance at the color, you should also check the key raw values in the table, which I will explain next. And “Caution” is not a maybe, it is an early warning system, and we have seen drives go from yellow to completely dead in a matter of days.

The SMART Values That Actually Matter

The big table looks intimidating, but only a handful of rows genuinely matter, and there is one column trick that trips up almost everyone.

Here is the key thing about reading any attribute: ignore the “Current” and “Worst” number columns and look at the Raw Values column. The Current value is a normalized score the drive calculates, but the Raw Value is the real count. For example, a Reallocated Sectors Count with a Current value of 100 and a Raw value of 0 is perfect. The same attribute showing Current 99 and Raw 48 means the drive has already remapped 48 bad sectors. Same-looking row, completely different reality. The raw value is where the truth lives.

For hard drives, these three are the ones that trigger a Caution and mean real trouble. Reallocated Sectors Count (ID 05) is the most common trigger: the drive found bad sectors and retired them, moving your data to spare sectors, and a rising count means it is running out of spares. Current Pending Sector Count (C5) means the drive found unstable sectors it cannot yet read and is waiting to remap them, often a sign of imminent failure. Uncorrectable Sector Count (C6) is the most serious: sectors that failed and could not be recovered at all, meaning some data may already be lost. Any non-zero raw value on C5 or C6 is a strong replace-the-drive signal.

For SSDs, the drive fails differently, so the numbers differ too. Watch Percentage Used or the equivalent SSD Life Left, which estimates how much of the drive’s rated write endurance you have consumed. Many SSDs flag Caution when remaining life drops to around 10%. You may also see Total Host Writes, which relates to the manufacturer’s TBW (terabytes written) rating. These are wear indicators rather than damage counters, since SSDs slowly wear out from writes rather than developing mechanical bad sectors.

Watch the Temperature Too

CrystalDiskInfo shows each drive’s current temperature, and it is worth a glance. For traditional hard drives, you want to stay below about 45 to 50°C under load, since sustained heat accelerates the wear on their moving parts. SSDs tolerate more, typically fine up to around 70°C, though NVMe drives often start throttling their speed around 60 to 65°C.

Temperature by itself will not instantly kill your data, but consistently high temperatures shorten a drive’s life and slow NVMe performance. If a drive runs hot all the time, the fix is usually better case airflow, the same principle behind keeping your other components cool. If you are already thinking about component heat, our guides on how to check your CPU temperature and GPU temperature cover the rest of the system, and better airflow helps all three at once.

What to Do When You See “Caution” or “Bad”

This is the moment that matters, so here is exactly what to do, and one hard truth first.

The hard truth: you cannot repair a failing drive. Physical sector damage cannot be undone. You cannot “fix” a Reallocated Sectors Count, because once a sector is retired it is gone forever and your drive’s usable lifespan has permanently shrunk. Any guide promising to “repair” these values is misleading you. The goal is not repair, it is rescuing your data and managing risk.

So the moment you see Caution or Bad, back up your important data immediately, before anything else. Copy your irreplaceable files to another healthy drive or the cloud right now, today, not this weekend. A drive in Caution can last months or die in days, and you cannot predict which. Once your data is safe, monitor the trend: set CrystalDiskInfo to resident mode (Function menu, then Resident) so it lives in your system tray and alerts you if the numbers get worse. If the reallocated or pending sector count keeps rising over the following days, the drive is actively failing and you should replace it. If a drive shows Bad, or holds the only copy of something you cannot lose, stop writing to it entirely and get the data off immediately, since continued use risks losing more.

One thing to avoid: some guides suggest dragging CrystalDiskInfo’s warning threshold slider to make the yellow Caution turn back to blue Good. That does not fix anything, it just hides the warning. The bad sectors are still there. Do not silence the alarm, act on it.

Set It and Forget It: Resident Mode

The best way to use CrystalDiskInfo is to not have to remember to use it. Open the Function menu and turn on Resident, and optionally Startup, so the tool runs quietly in your system tray and launches with Windows. From then on it monitors your drives continuously and pops an alert the instant a health status changes from Good to Caution. This turns a tool you would otherwise forget about into a genuine early-warning system that watches your data around the clock for free.

For anyone who keeps important files on their PC, this five-second setup is the single most valuable thing in this guide.

CrystalDiskInfo vs CrystalDiskMark: Not the Same Thing

People mix these up constantly, so here is the quick distinction. CrystalDiskInfo checks your drive’s health, the S.M.A.R.T. data, temperature, and wear covered in this guide. CrystalDiskMark, its companion tool from the same developer, measures your drive’s speed, the read and write performance. One tells you if your drive is dying, the other tells you how fast it is. They pair well: use CrystalDiskInfo to confirm the drive is healthy, then CrystalDiskMark to check it is hitting its rated speeds. If you want to benchmark your whole system rather than just storage, our roundup of free PC benchmark software covers the best tools for CPU, GPU, and drives together.

Common Patterns I Keep Seeing

These are the situations that come up again and again whenever people run CrystalDiskInfo, and they show how easy it is to misread a healthy or a failing drive.

The most common by far is the person who runs it out of curiosity, sees a yellow Caution, and does nothing because the PC still works fine. Weeks later the drive dies and takes their files with it. The drive was warning them the whole time. Caution means back up now, not “keep using it until it breaks.”

The opposite pattern is the panic over a single reallocated sector. Someone sees a Raw value of 1 on Reallocated Sectors, assumes the drive is dead, and rushes to replace a perfectly usable drive. One reallocated sector that never increases is often harmless, plenty of drives live for years with a small, stable count. The thing to watch is not the number itself but whether it keeps climbing. A count that jumps from 1 to 20 to 200 is a dying drive; a count that sits at 1 for two years is not.

Then there is the confusion over a brand-new SSD showing scary-looking numbers. New drives sometimes display high Total Host Writes or odd vendor-specific attributes that look alarming but are completely normal, because SSD manufacturers report health differently and CrystalDiskInfo shows the raw data. When in doubt, the Health Status box and the Percentage Used are the reliable summary, not one unfamiliar row.

And the classic false alarm: a perfectly healthy external drive showing Unknown or no S.M.A.R.T. data. That is not a failing drive, it is the USB enclosure blocking the health data from getting through. Connect the same drive directly by SATA and it usually reports fine.

FAQs

Is CrystalDiskInfo safe to use?

Yes. CrystalDiskInfo is free, open-source, and widely trusted, and it only reads your drive’s existing S.M.A.R.T. data, it does not modify anything. Just download it from the official crystalmark.info site, since disk tools are sometimes faked with malware on unofficial download sites.

Is CrystalDiskInfo free?

Completely. It is free and open source with no paid tier, so you never need to buy a “premium” drive health tool. Anything a paid disk-health app offers, CrystalDiskInfo already does for nothing.

What does Caution mean in CrystalDiskInfo?

Caution (yellow) means at least one degradation counter is non-zero, usually reallocated, pending, or uncorrectable sectors. The drive still works, but it is developing problems. Treat it as a warning to back up your data immediately and start watching the trend closely.

Can I still use a drive showing Caution?

Short-term, often yes, but treat it as living on borrowed time. Back up everything important right away, then monitor whether the sector counts are rising. If they climb, replace the drive. A Caution drive can survive months or fail within days, and there is no reliable way to predict which.

Can CrystalDiskInfo fix a failing drive?

No, and be wary of any guide claiming otherwise. Physical drive damage is permanent and cannot be repaired. CrystalDiskInfo is a diagnostic tool that tells you a drive is failing so you can rescue your data, not a repair tool. Dragging the warning slider only hides the alert, it does not fix anything.

Does “Good” health status mean my drive is fine?

Mostly, but not as a guarantee. Good only means no attribute has crossed its failure threshold yet. A drive can show Good while already having a small non-zero reallocated sector count. For peace of mind, glance at the raw values of the key sector attributes, not just the color.

How do I read the SMART values?

Look at the Raw Values column, not the Current or Worst columns. The raw value is the real count. For hard drives, watch Reallocated Sectors (05), Current Pending Sectors (C5), and Uncorrectable Sectors (C6). For SSDs, watch Percentage Used or SSD Life Left. Zero raw values on the sector attributes is what you want.

What temperature is safe for my drive?

For hard drives, stay under about 45 to 50°C under load. SSDs are fine up to around 70°C, though NVMe drives may throttle around 60 to 65°C. Occasional spikes are fine, but a drive that runs hot constantly will wear faster, so improve your case airflow if temperatures stay high.

Does CrystalDiskInfo work on SSDs and NVMe drives?

Yes, it supports HDDs, SATA SSDs, NVMe drives, and many external USB drives. The specific attributes it shows differ between HDDs and SSDs because they fail in different ways, mechanical wear versus write endurance, but it reads health for all of them.

How often should I check my drive health?

For a normal drive that shows Good, once a month is plenty. The smarter approach is to enable Resident mode so CrystalDiskInfo monitors continuously and alerts you automatically. For a used or suspect drive, check daily for a week, then weekly, watching for any rising sector counts.

Wrapping Up

CrystalDiskInfo is one of the highest-value free tools you can put on a PC, because it turns your drive’s silent, hidden health data into a clear warning you can actually act on. Download it from the official site, glance at the Health Status box, and if you ever see yellow or red, back up your data immediately, that single habit will save you from the worst kind of data loss.

Keep two honest truths in mind. A “Good” status is reassuring but not a guarantee, so it is worth a monthly glance and Resident mode running in the background. And a failing drive cannot be repaired, only rescued, so the moment you see Caution, your job is to save your files, not to fix the drive. Do that, and you will never be caught off guard the way I almost was.