How to use
- Close downloads and heavy programs so they do not disturb the test.
- Choose the test size (larger is more accurate) and press start.
- The test writes and reads the file in big blocks, then in small 4 KB pieces at random places.
- The temporary file is deleted automatically when the test ends.
Frequently asked questions
Why is this lower than CrystalDiskMark?
The browser adds its own layer between the page and the disk, and the operating system cache can make reads look faster. Use the results to compare devices and browsers, or to spot a clearly slow or failing drive.
What are good values?
NVMe SSDs usually show hundreds to thousands of MB/s sequentially, SATA SSDs a few hundred, hard disks and eMMC storage 50–150 MB/s. 4 KB random speed matters most for how fast apps and the system feel.
Does the test wear out my SSD?
Writing up to 1 GB once is negligible: modern SSDs are rated for hundreds of terabytes.
Is anything left on my device?
No. The test file lives in the site's private storage and is deleted at the end, even if the test fails.