It does not simply measure theoretical maximum read/write speeds. Instead, it simulates real-world video workloads and answers one critical question: "Is my drive fast enough to handle this specific video format?" The app writes (then reads) a large block of test data—typically 5 GB by default—to the target drive. It measures the sustained performance, not just burst speeds (which are often misleading for video work).
macOS 10.13 or later (Apple Silicon native). blackmagic disk speed test mac
| Drive Type | Typical Write Speed | Video Capability | | :--- | :--- | :--- | | | 50–90 MB/s | 1080p ProRes 422 (maybe) | | 7200 RPM HDD | 120–180 MB/s | 1080p ProRes 422 HQ | | SATA SSD (2.5") | 450–520 MB/s | 4K ProRes 422 HQ / 4K RAW (light) | | NVMe SSD (PCIe 3.0) | 1,500–3,000 MB/s | 8K ProRes 4444 / 6K RAW | | NVMe SSD (PCIe 4.0) | 5,000–7,000+ MB/s | 8K RAW, 12K Blackmagic RAW | | Thunderbolt 3/4 RAID | 2,000–5,000+ MB/s | Multi-stream 8K editing | It does not simply measure theoretical maximum read/write