How to get Block size base on OS

For Windows on Intel.
1. For window on Intel default size is 512 byte, but you can change it by pre-formatting hard drive.

2. Use fsutil fsinfo ntfsinfo c: to get

c:\>fsutil fsinfo ntfsinfo c:
NTFS Volume Serial Number : 0x1e345b64345b3e49
Version : 3.1
Number Sectors : 0x0000000004a852c0
Total Clusters : 0x0000000000950a58
Free Clusters : 0x00000000003ae433
Total Reserved : 0x0000000000000000
Bytes Per Sector : 512
Bytes Per Cluster : 4096 -- this is answer
Bytes Per FileRecord Segment : 1024
Clusters Per FileRecord Segment : 0
Mft Valid Data Length : 0x000000000d72a000
Mft Start Lcn : 0x00000000000c0000
Mft2 Start Lcn : 0x00000000004a852c
Mft Zone Start : 0x0000000000800020
Mft Zone End : 0x000000000083b520

3. To get all possible OS block sizes use
c:\ format /?

4. In explorer select your hard drive, click right button, select "Format..."
from
context menu, and see your OS block size as "Allocation unit size".

Redhat linux on Intel
dump2fs /dev/hda