Hard drives and SSDs fail without warning. The only way to catch a problem before you lose data is to check the drive’s health proactively, using SMART data, Windows diagnostic tools, or third-party software that interprets the raw numbers in a readable format. Most drives give you weeks or months of warning before they fail completely.
This guide covers every practical method for checking disk health on Windows, from a quick command-line SMART check to a full surface scan with chkdsk, plus the physical warning signs worth knowing before any of that.
Quick Answer
Open an elevated Command Prompt and run wmic diskdrive get status. If the result says “OK” for every drive, your disk health is currently good. For a full SMART report, run chkdsk C: /f /r (requires a restart) to scan for bad sectors and file system errors. For detailed SMART attribute data, download HDDScan (free) and check attributes like #5 Reallocated Sector Count, #197 Current Pending Sector, and #198 Uncorrectable Sector Count.
Recognize Physical Warning Signs
Before running any software check, it helps to know what a failing drive feels like. Hard disk drives often show physical symptoms days or weeks before they die completely, and recognizing these early can give you time to back up and replace the drive before total failure.
Clicking or grinding noises from a traditional hard drive are a serious warning. These sounds typically mean the read/write head is struggling to position itself correctly, often because the platter surface has degraded or the head itself is damaged. A drive making these noises should be treated as a near-failure and backed up immediately.
Slower-than-usual boot times and file access that takes noticeably longer than before can indicate the drive is working harder to read data from sectors that are starting to fail. If your system that used to boot in 30 seconds is now taking two minutes and you have not installed anything new, check the drive health.
Frequent freezing during file operations, especially when copying files or opening large documents, is another common sign. Files or folders that Windows reports as corrupted or unreadable, or that disappear unexpectedly, often point to bad sectors developing on the drive surface. SSDs exhibit similar symptoms without the noise, typically showing as corrupted files, sudden performance drops, or data that was written correctly but reads back as garbage.
Check via Command Prompt
Windows includes two built-in command-line tools that can check disk health: the WMIC disk status command for a quick SMART overview, and chkdsk for a thorough scan of the file system and disk surface.
Check SMART Status with WMIC
- Open the Start menu, search for cmd, right-click it, and select Run as administrator.
- Type the following command and press Enter:
wmic diskdrive get statusIf the result is “OK” for every drive listed, the SMART firmware is reporting no immediate failures. If you see “Pred Fail” or “Bad,” the drive is reporting imminent failure and you should back up immediately. If you see “Unknown,” the drive’s SMART data is not accessible, which usually means a USB enclosure is blocking the SMART queries.
Run CHKDSK for a Full Surface Scan
CHKDSK scans the disk surface for bad sectors and verifies the integrity of every file system structure. It takes longer than the WMIC check but provides much more detail.
- In the same elevated Command Prompt, type the following and press Enter:
chkdsk C: /f /r- Windows will prompt you to schedule the scan for the next restart since the C: drive is in use. Type Y and press Enter, then restart your computer.
The /f flag fixes file system errors, and /r scans for and recovers data from bad sectors. The scan can take 30 minutes to several hours depending on drive size. Results are logged to the Event Viewer under Windows Logs > Application, with source “Wininit.”
Use Windows Check Disk Tool
If you prefer a graphical interface, Windows has a built-in Check Disk tool accessible through File Explorer that runs the same chkdsk checks without needing a Command Prompt.
- Open File Explorer and right-click the drive you want to check.
- Select Properties.
- Go to the Tools tab and click Check under Error checking.
- Click Scan drive in the dialog that appears.
Windows scans the drive and reports any errors it finds. For the system drive (C:), it will schedule the scan at the next restart, the same behavior as chkdsk from Command Prompt.
Use HDDScan for Detailed SMART Data
HDDScan is a free tool that reads all available SMART attributes from your drive and presents them in a clear table with pass/fail indicators. This is more useful than the simple OK/Fail output from WMIC because it shows exactly which attributes are degrading, allowing you to judge how much life the drive has left.
Download and Install HDDScan
- Go to hddscan.com and download the latest version.
- Extract the zip and run HDDScan.exe. No installation is required.
Read SMART Attributes
- Select your drive from the dropdown at the top of the HDDScan window.
- Click SMART to open the attribute table.
- Focus on these critical attributes. Any value above zero in the “Raw” column for these is a warning:
- #5 Reallocated Sector Count — sectors the drive has marked as bad and swapped for spares from the reserve pool. Any non-zero value means physical damage has already occurred.
- #197 Current Pending Sector — sectors that are unstable and waiting to be tested during the next write. Non-zero means the drive is actively dealing with questionable sectors.
- #198 Uncorrectable Sector Count — sectors that failed and could not be recovered. Non-zero is a serious warning requiring immediate backup.
A drive with a Reallocated Sector Count above 50 or any non-zero value in attribute #198 should be replaced soon, even if it is still functioning. The reserve sectors that the drive uses to substitute for failed ones will eventually run out.