HDD Health Monitor Free HDD S.M.A.R.T. Health Monitor for Windows
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Author: Ari Sohandri Putra · ARImetic Inc.
Sponsor: <https://github.com/sponsors/arisohandriputra/>

1. Overview

HDD Health Monitor is a 100% free and open-source Windows utility that reads raw S.M.A.R.T. (Self-Monitoring, Analysis and Reporting Technology) data directly from your physical drives and presents it in a clean, easy-to-read interface.

S.M.A.R.T. is a built-in system found in almost every modern hard disk drive (HDD), solid-state drive (SSD), NVMe drive, and many USB-connected drives. It continuously collects dozens of internal measurements - such as read error rates, temperatures, reallocated sectors, and power-on hours - that can indicate whether a drive is healthy or starting to fail.

HDD Health Monitor makes all of this information visible to you at a glance, warns you before problems become data loss, and keeps a historical record so you can track changes over time.

2. System Requirements

3. Getting Started

1. Download HDDHealthmonitor.exe from the official release page.
2. The program scans all physical drives automatically on startup. No configuration is needed.
3. If you have more than one drive, click the drive buttons along the top of the window to switch between them.
4. The S.M.A.R.T. data refreshes every 5 seconds automatically.

The program is a single .exe file - there is no installer, no setup wizard, and nothing is written to your registry during normal use. You can run it directly from any folder, a USB stick, or your Desktop.

4. Main Window

The main window is divided into several areas:

5. Health & Performance Meters

Health Percentage

The Health % figure gives you a single number (0–100%) that summarizes the condition of your drive. It is calculated from the S.M.A.R.T. attribute values reported by the drive itself:

For NVMe drives, health is calculated from the drive's own Health Information Log (Log Page 02h), which includes percentage-used lifetime, available spare, and critical warning flags.

Performance Percentage

The Performance % meter reflects how well the drive is performing relative to its rated capabilities, based on attributes such as seek error rate, throughput performance, and spin-up time. A new drive typically shows close to 100%. Mechanical wear and increasing error rates will lower this figure over time.

6. S.M.A.R.T. Attribute Table

The attribute table lists every S.M.A.R.T. measurement reported by the currently selected drive. Each row contains:

Tip: The most important attributes to watch on a traditional HDD are Reallocated Sectors Count (ID 05h), Current Pending Sectors (ID C5h), Uncorrectable Sectors (ID C6h), and Reallocation Event Count (ID C4h). Any non-zero raw value in those four attributes is a warning sign and should not be ignored. For SSDs, also watch Remaining Life Percentage (ID A9h / E7h) and Program Fail Count (ID ABh).

7. Alerts & Notifications

HDD Health Monitor watches your drives in the background and pops up a Windows tray balloon notification the moment a problem is detected. You do not need to keep the window open - as long as the program is running (even minimized to tray), alerts will appear.

The following conditions trigger automatic notifications:

Each alert is sent only once per session to avoid flooding you with repeated notifications. If the condition clears (e.g., temperature drops back below the warning threshold) and then returns, the alert will fire again.

8. History Graph

The History Graph window lets you see how a drive's health has changed over time. To open it, click the History Graph button in the main window, or go to View → History Graph.

What the history graph shows:

• Overall health percentage plotted over time as a line graph.
• Individual S.M.A.R.T. attribute values - you can select which attribute to plot from the drop-down list inside the graph window.
• Each data point represents one recorded snapshot. Snapshots are taken automatically every time the program refreshes drive data (every 5 seconds while running).

The history data is saved to disk so it persists between sessions - you can close and reopen the program and still see the trend from previous days or weeks.

Tip: Use the history graph to spot gradual deterioration that might not be obvious from a single reading. A slowly rising temperature or a slowly increasing reallocated sector count over weeks is a clear early-warning sign.

9. System Tray

HDD Health Monitor places an icon in the Windows system tray (notification area, bottom-right of the taskbar) for every detected drive. Each tray icon shows the drive's current health percentage as a small colored number:

Right-clicking a tray icon shows a small menu with two options:

• Open HDDHealth Monitor > brings the main window back to focus.
• Exit > closes the program completely.

When you click the window's close button (×), the program minimizes to tray rather than quitting, so monitoring and alerts continue running in the background. To exit fully, use File → Exit or right-click the tray icon and choose Exit.

10. Save Screenshot

You can save a PNG image of the main window at any time. This is useful for sharing your drive's S.M.A.R.T. data with a technician or posting it in a support forum.

To save a screenshot:

• Go to File → Save Screenshot, or press Ctrl+S.
• The image is saved automatically - no file dialog appears.
• The file is saved in your Documents folder under a subfolder called HDDH_Screenshots\, with a filename that includes the date and time (e.g., HDDH_20260622_143055.png).
• After saving, a confirmation dialog appears with the full file path and an option to open the screenshots folder immediately.

11. Hot-Plug (USB Drive Detection)

HDD Health Monitor is hot-plug aware. When you connect a USB drive while the program is running, it automatically detects the new drive and adds it to the drive selector within about 1–2 seconds. No restart is required.

Similarly, when you safely remove or unplug a USB drive, the program removes its button and tray icon automatically.

Note: Whether S.M.A.R.T. data is available for a USB drive depends on the USB bridge chip inside the drive enclosure. See Section 12 for supported USB bridge chips.

12. Supported Drive Types & Controllers

HDD Health Monitor supports the following drive types and uses the appropriate low-level communication method for each:

Note: If your USB drive enclosure uses a bridge chip not listed above, the program will still attempt a generic SAT connection. If that fails, the S.M.A.R.T. data will not be available but the drive will still appear in the drive list with its model and capacity.

13. Supported Drive Vendors

HDD Health Monitor recognizes drives from the following manufacturers and applies any vendor-specific S.M.A.R.T. attribute mappings automatically:

14. S.M.A.R.T. Attribute Reference

The table below lists all S.M.A.R.T. attributes that HDD Health Monitor can display, their IDs, and what they mean in plain language. Not every drive reports every attribute - you will only see the ones your particular drive supports.

Criticality key:
● Critical > A non-zero raw value or a failed threshold is a serious warning sign. Back up your data immediately.
● Advisory > Worth watching; deterioration here may indicate developing problems.
○ Informational > Normal operational counters; not directly linked to failure prediction.

Standard ATA S.M.A.R.T. Attributes

SSD-Specific Attributes

NVMe Health Log Attributes

For NVMe drives, the following values from the NVMe Health Information Log (Log Page 02h) are displayed:

15. Menus & Keyboard Shortcuts

16. Frequently Asked Questions

Q: The attribute table shows "Run as Administrator and click Refresh". What do I do?
A: Close the program, then right-click HDDHealthmonitor.exe and choose Run as administrator. S.M.A.R.T. data requires administrator-level access to the Windows kernel driver.

Q: My USB drive shows up but the S.M.A.R.T. table is empty or shows no data.
A: The USB bridge chip inside your enclosure may not support S.M.A.R.T. pass-through, or it may use a protocol not yet supported. The drive will still appear in the list with its model name and capacity, but health data will not be available. Try a different enclosure if you need S.M.A.R.T. readings from that drive.

Q: I see a non-zero Reallocated Sectors count. Should I be worried?
A: Yes. Even a single reallocated sector means the drive has found a bad spot on the disk and moved data away from it. A small count (1–5) on an older drive may be stable for a long time, but any non-zero value is a signal to back up your data now and replace the drive when convenient. A rising count is urgent - replace the drive immediately.

Q: The health percentage suddenly dropped. Is the drive about to fail?
A: A sudden drop usually means a new S.M.A.R.T. attribute has crossed its threshold or a critical raw value (like pending sectors) has appeared. Check the attribute table for any rows showing WARNING or FAILED status. Back up your data as a precaution and monitor the drive closely over the next few days.

Q: My NVMe drive's "Percentage Used" shows 0%. Is it new?
A: Not necessarily - it means less than 1% of the rated write endurance has been consumed. NVMe drives with heavy workloads will show increasing values over months or years. The drive is perfectly fine until this number approaches 100%.

Q: The temperature alert fired but my room is cool. Is something wrong?
A: The alert threshold is 55 °C (warning) and 65 °C (critical). HDDs and SSDs run hotter than room temperature, especially under load or in enclosed cases with poor airflow. Check that your PC case fans are working and that the drive has adequate clearance. Sustained temperatures above 55 °C will shorten the drive's lifespan.

Q: How do I stop the program from running in the background?
A: Right-click the tray icon and choose Exit, or go to File → Exit. Simply closing the main window only minimizes the program to the tray; it keeps running until you explicitly exit.

Q: Can I run this on more than one drive at the same time?
A: Yes. HDD Health Monitor scans and monitors all physical drives simultaneously. Each drive gets its own tray icon, and alerts are generated independently for each. Use the drive selector buttons at the top of the window to switch the detail view between drives.

Q: Where are the history files stored?
A: History data is saved alongside the executable in the same folder where HDDHealthmonitor.exe is located, so keep the program in a folder where you have write permission (not in C:\Program Files\ unless you run as Administrator).

Q: Is this program free? Does it expire?
A: Yes, HDD Health Monitor is 100% free and open-source software (MIT License). It does not expire, does not nag, and does not require registration. If you find it useful, consider supporting the author via GitHub Sponsors.

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