how to test RAM speed on Mac

In this post I’ll show you a way how to test RAM speed on Mac.

First we will create a virtual disk that resides in RAM.
Open Terminal and type:

diskutil erasevolume HFS+ “RAMDisk” `hdiutil attach -nomount ram://16777216`

…this will create a 8GB RAM disk

If you need different size, multiply 2048 by the number of MB you wish to use for the RAM disk. Here are some examples:

  • 256 MB = 524288
  • 512 MB = 1048576
  • 1 GB = 2097152
  • 2 GB = 4194304

As a next step, download Blackmagic Disk Speed Test from AppStore. Select RAMDisk as a destination in settings. You may also want to change the sample size between 1-5 GB

Here’s an example test result:

DDR4 memory that runs at 3000MHz tops at 6885 Write / 5420 Read when measured.