Mac OS Extended Format (HFS+): Default Allocation Block Size

This article provides a table that lists the default allocation block size for Mac OS Extended format volumes of various sizes.
Volume Size
Default Allocation Block Size
<=256 MB
512 bytes
256 MB <= 512 MB
1024 bytes (1K)
512 MB <= 1 GB
2048 bytes (2K)
> 1 GB
4096 bytes (4K)
Published Date: Feb 18, 2012