cluster sizes

Each operating system has its own terminology;
Microsoft uses cluster,
Apple uses allocation block.

Operating system (file system type)	Disk size
	<256mb	up to 512MB	up to 1GB	up to 2GB	up to 8GB	up to 16GB	> 16GB
DOS & Windows 95 (FAT16)	4K	8K	16K	32K	N/A (FAT16 can't handle drives > 4GB)
Win95 OSR2 & Win98 (FAT32)	N/A	4K				8K	16K or 32K
Windows NT (NTFS)	0.5K to 64K (0.5K to 4K clusters are most common)
MacOS pre-8.1 (HFS)	0.5K - 4K	4.5K - 8K	8.5K - 16K	16.5K - 32K	N/A (HFS can't handle disks > 2GB)
MacOS 8.1 and later (HFS+)	0.5K	1K	2K	Default is 4K; user-selectable up to 4K
CD-ROM, 650MB (ISO 9660)	always 2K
DVD-ROM (UDF)	always 2K