How to Do a Disk Check on Windows and Mac

Your hard drive or SSD works quietly in the background — until it doesn't. A disk check is one of the most reliable ways to catch storage problems before they cause data loss, slow performance, or system crashes. Whether you're troubleshooting a sluggish PC or doing routine maintenance, knowing how to run a disk check is a foundational skill for anyone managing their own computer.

What a Disk Check Actually Does

A disk check scans your storage drive for two broad categories of problems:

File system errors — These are logical problems with how your operating system organizes and tracks files. They can appear after an improper shutdown, a failed software update, or corrupted data writes. The OS can usually repair these automatically.

Bad sectors — These are physical or logical areas of a drive that can no longer reliably store data. On traditional HDDs (hard disk drives), bad sectors often indicate physical wear or damage. On SSDs (solid-state drives), they're more likely to be logical errors, though SSDs have their own failure patterns related to NAND cell degradation.

A disk check tool reads the drive, maps any problem areas, and in most cases attempts to repair what it can — or at minimum flags what it finds so you can act on it.

How to Run a Disk Check on Windows 💻

Windows includes a built-in tool called CHKDSK (Check Disk), which has been part of the OS for decades. There are two main ways to access it.

Method 1: Through File Explorer

1. Open File Explorer and go to This PC
2. Right-click the drive you want to check (usually C:)
3. Select Properties → click the Tools tab
4. Under Error checking, click Check
5. Windows will either report no errors or offer to scan and repair

This method is straightforward and doesn't require technical knowledge. If Windows finds no issues, it may tell you the drive doesn't need scanning — though you can force a scan anyway.

Method 2: Using Command Prompt

For more control, run CHKDSK directly:

1. Open Command Prompt as Administrator (search "cmd," right-click, run as admin)
2. Type the command: chkdsk C: /f /r and press Enter
3. The /f flag fixes file system errors; the /r flag locates bad sectors and recovers readable data
4. If scanning the system drive (C:), Windows will schedule the check to run on the next restart

Note: CHKDSK on a full-featured scan (/r) can take a significant amount of time — anywhere from minutes to several hours depending on drive size and condition.

Windows 10 and 11 Differences

The graphical interface and background scanning behavior are slightly different between Windows 10 and 11, but the core CHKDSK functionality works the same in both versions.

How to Run a Disk Check on macOS 🍎

Mac users have access to a tool called Disk Utility, which includes a feature called First Aid.

1. Open Disk Utility (found in Applications → Utilities, or via Spotlight search)
2. Select the drive or volume you want to check from the left sidebar
3. Click First Aid at the top of the window
4. Click Run to start the scan

First Aid checks the drive for errors in the file system and repairs what it can. If it finds problems it can't fix while the drive is mounted and in use, you may need to boot from macOS Recovery (hold Command + R at startup on Intel Macs, or hold the power button on Apple Silicon Macs) and run First Aid from there.

HDD vs. SSD: Does It Matter for Disk Checks?

Yes — and understanding the difference shapes how you interpret results.

For SSDs, disk checks are useful but tell only part of the story. S.M.A.R.T. (Self-Monitoring, Analysis, and Reporting Technology) data — which tracks drive health metrics like reallocated sectors, wear leveling counts, and read error rates — is often more informative. Tools like CrystalDiskInfo (Windows) or DriveDx (Mac) can surface this data in readable form.

When and How Often to Run a Disk Check

There's no single universal schedule, but common triggers include:

• After an unexpected shutdown or power loss
• When the system is running noticeably slower than usual
• Before and after cloning or migrating a drive
• When files are unexpectedly corrupted or missing
• As part of routine system maintenance every few months

Running a disk check proactively — rather than only when something goes wrong — gives you early warning of a failing drive while you still have time to back up your data.

Variables That Shape Your Experience

The outcome of a disk check isn't the same for every user. A few factors significantly affect what you encounter:

• Drive age and type — A five-year-old HDD has more wear history than a brand-new SSD; the same error count can mean something very different
• Drive size — Scanning a 4TB HDD takes substantially longer than a 256GB SSD
• Current drive usage — Heavily fragmented or near-full drives may surface more errors
• OS version and file system — NTFS, FAT32, exFAT, APFS, and HFS+ each have different error patterns and repair capabilities
• Technical comfort level — Command-line tools offer more granular control, but the GUI options are sufficient for most use cases

What a disk check reveals — and what you should do about it — depends heavily on which of these variables apply to your specific drive and situation.