H2Testw

H2testw is the standard freeware utility used to test the real speed and storage capacity of flash drives, SD cards, external HDDs, and SSDs. It scans a drive sector by sector to confirm the device actually holds the capacity it claims, flagging bad sectors and read/write errors along the way.

The PC hardware community most commonly uses it to catch two critical issues:

• Failing Hardware: To check genuine storage drives that are aging and developing bad sectors or unstable flash memory components.
• Fake storage device: Fake drives sold as 64GB, 128GB, or 512GB that are physically only 8GB, using hacked firmware to trick your operating system into showing an incorrect size.

If you have ever bought a pen drive or MicroSD card online that seemed to hold less data than advertised or copied files that later became corrupted and unreadable, H2testw is the exact tool built to diagnose the problem.

H2testw Overview

H2testw is a portable application, meaning it requires zero installation. Download the zip archive below, extract the executable file, and run it directly on your system.

Specification	Details
Software Name	H2testw
File Name	h2testw_1.4.zip / h2testw.exe
Latest Version	v1.4 (Official Stable Release)
License Type	Freeware
File Size	213 KB
Developer	Harald Bögeholz (c’t Magazine / Heise Medien)

[ Download H2testw v1.4 (Direct ZIP Link) ]

(Note: H2testw works natively on Windows. For macOS and Linux systems, please see the compatibility layout notes below.

What Is H2Testw?

H2testw was developed by German programmer Harald Bögeholz as part of a broader effort by c’t magazine to detect counterfeit storage devices flooding the market. The tool writes test data across the entire drive, then reads it back and verifies every byte matches what was written. If the drive’s real capacity is smaller than what it reports to your operating system, the mismatch shows up immediately.

Example: A 64GB HP USB 3.2 flash drive should report roughly 57.7GB of usable space after formatting overhead (this is normal — it’s not a defect). If H2testw shows a much smaller usable capacity than that, or throws read/write errors, that’s a sign of a fake or failing drive.

How Does H2Testw Work?

H2testw runs a write-and-verify test: it fills your selected drive with test data, then reads every sector back and checks it against what was written.

1. Plug in the storage device you want to test.
2. Open H2testw and select the drive from the list.
3. Start the test; it writes data across the full drive, then verifies it.
4. Review the results: actual capacity, any errors found, and average read/write speed.

Because the tool writes and reads the entire drive, it also reports real-world transfer speeds, which is useful if you’re comparing drives or checking whether a device is performing as advertised.

Features of H2testw

• Lightweight and fully portable -no installation required
• Simple, no-frills interface
• Works with USB flash drives, SD/microSD cards, external HDDs, and SSDs
• Detects fake or inflated capacity claims
• Detects bad sectors and read/write errors
• Reports real write and read speeds
• Compatible with Windows and macOS (via F3XSwift, see below)

Is H2Testw Safe to Download?

Yes, H2testw is free to use without any license fees, hidden paywalls, or feature restrictions. A few notes for safe use:

• Download only from the official developer source or a verified mirror (linked below), not from random file-sharing sites.
• The tool does not require installation and does not modify system files outside the drive you explicitly select.

Important: H2testw writes over all existing data on the drive you test. Back up anything important before running it.

How to Use H2Testw

Testing a full drive takes time, since the tool writes and then reads back every sector. A large card can take several hours. This is normal and means the test is working correctly, not stuck.

Steps:

1. Download the H2Testw ZIP file (link above).
2. Extract h2testw.exe from the ZIP folder.
3. Plug your USB drive, SD card, or external HDD into your PC.
4. Run h2testw.exe.
5. Select “English” as the language.
6. Click Select target and choose your drive’s letter.
7. Make sure all available space is selected.
8. Click Write + Verify.
9. Wait for the test to finish, and then review the report.

Read more: How long does H2testw take?

H2Testw on Mac

H2testw itself is a Windows tool, but Mac users can get equivalent results with F3XSwift, a native macOS port that performs the same write-and-verify capacity test. See our H2testw for Mac guide for setup steps.

FAQs