Blackmagic Disk Speed Test Alternatives for Mac
If you need to measure the read and write speed of a drive on your Mac, Blackmagic Disk Speed Test is a popular choice, but several solid alternatives exist, including AmorphousDiskMark, AJA System Test Lite, and the built-in command-line tool dd. These alternatives offer different features, from more detailed benchmarks to free and open-source options, and this article explains what they are, how they work, and how to choose one.
Why You Might Need an Alternative
Blackmagic Disk Speed Test is free and widely used, but it has limitations. It only tests sequential read/write speeds with a single test size, and it doesn’t show random 4K performance, which matters for everyday tasks like launching apps or opening many small files. Some users also find its interface too simple or want more control over test parameters. Alternatives can provide deeper insights, support more file systems, or simply offer a different workflow that better fits your needs.
What the Tests Actually Measure
Disk speed tests measure how quickly data can be read from or written to a storage device. The two main categories are:
- Sequential speed: Transferring one large, continuous block of data (like copying a movie file). This is what most simple tools report.
- Random speed: Reading or writing many small blocks scattered across the disk (like opening a folder full of photos). This is more representative of real-world usage.
Most Mac alternatives let you choose the test file size and sometimes the queue depth (how many operations are sent at once). A higher queue depth can simulate heavy multitasking.
Top Alternatives for Mac
1. AmorphousDiskMark
This free, open-source tool is heavily inspired by the Windows program CrystalDiskMark. It tests both sequential and random speeds at different queue depths (QD1 and QD8) and reports results in MB/s and IOPS (input/output operations per second). It’s available on the Mac App Store and is a good all-round choice for a detailed look at your drive’s performance.
2. AJA System Test Lite
Developed by AJA Video Systems, this free tool is designed for video professionals but works for any drive. It lets you choose a video resolution and codec to simulate real video capture/playback workloads, and it reports both read and write speeds. It’s particularly useful if you’re checking whether a drive can handle 4K or 8K video editing.
3. Disk Speed Test (by Moinul)
Not to be confused with Blackmagic’s tool, this is a simple, free app that measures sequential read/write speeds. It has a clean interface and supports multiple test sizes. It’s less feature-rich than others but is a quick, no-frills option.
4. iostat and dd (Terminal)
macOS includes command-line utilities that can measure disk performance. dd can write a file and time it, and iostat shows real-time disk activity. These are free and built-in, but they require comfort with the Terminal and don’t give a fancy GUI. For example, to test write speed:
dd if=/dev/zero of=~/testfile bs=1m count=1024 conv=fdatasyncThis writes a 1GB file and reports the speed. To test read speed, use dd if=~/testfile of=/dev/null bs=1m. Remember to delete the test file afterward.
5. QuickBench
QuickBench is a commercial tool (around $10) that offers extensive testing options, including sequential, random, and mixed workloads. It can test multiple volumes at once and has a more professional interface. It’s a good choice if you need advanced diagnostics.
How to Choose the Right Tool
Consider what you need the test for:
- Quick check: Use AmorphousDiskMark or Disk Speed Test (Moinul) for a fast, easy result.
- Video editing: AJA System Test Lite is ideal because it simulates video workloads.
- Deep analysis: QuickBench or AmorphousDiskMark with random tests gives you a fuller picture.
- No installs: Use
ddin Terminal.
Also, ensure the tool supports the file system you’re using (APFS, HFS+, exFAT, etc.). Most do, but it’s worth checking.
Common Mistakes and Misconceptions
One common mistake is testing a drive that is nearly full. Performance can degrade as a drive fills up, so always test with at least 20-30% free space. Another is not closing other apps during the test; background activity can skew results. Also, be aware that USB-C or Thunderbolt connections have different maximum speeds—a drive might be faster than the connection allows, so check the interface spec. Finally, don’t compare results from different tools directly; each uses different test sizes and methods, so numbers will vary.
How to Interpret the Results
Read speed is usually higher than write speed on most drives. For SSDs, sequential speeds of 500 MB/s (SATA) to 3000+ MB/s (NVMe) are typical. Random 4K speeds are much lower—often under 100 MB/s—but are more important for everyday responsiveness. If you see a big gap between sequential and random speeds, that’s normal. If a drive is performing far below its rated speed, check the connection, cable, and whether the drive is failing.
Frequently Asked Questions
Is Blackmagic Disk Speed Test free?
Yes, Blackmagic Disk Speed Test is free and available on the Mac App Store. It’s a popular choice, but it only tests sequential speeds, which is why some users look for alternatives.
Can I test the internal SSD of my Mac?
Yes, all these tools can test internal drives. However, be cautious with dd—writing a large file to your startup disk can temporarily fill it up. Always use a small test file and delete it afterward.
Do these tools work on APFS and HFS+?
Yes, most modern tools support APFS and HFS+. They also work on exFAT and FAT32, but note that some file systems have overhead that affects results.
Why do my results vary between tests?
Disk performance can fluctuate due to background processes, thermal throttling, and the drive’s cache. Run multiple tests and take the average. Also, ensure the drive is idle and not being used by Time Machine or Spotlight indexing.
Are there any web-based disk speed tests?
No, web-based tests cannot accurately measure local disk speed because they run in a browser sandbox. You need a native app or command-line tool.
What is IOPS and why does it matter?
IOPS stands for Input/Output Operations Per Second. It measures how many read/write operations a drive can handle per second, which is critical for databases and heavy multitasking. Tools like AmorphousDiskMark report this metric.
Related
Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.