| Volume Size | FAT16 Cluster Size | FAT32 Cluster Size | NTFS Cluster Size |
|---|---|---|---|
| 7 MB–16 MB | 2 KB | Not supported | 512 B |
| 17 MB–32 MB | 512 B | ||
| 33 MB–64 MB | 1 KB | 512 B | |
| 65 MB–128 MB | 2 KB | 1 KB | |
| 129 MB–256 MB | 4 KB | 2 KB | |
| 257 MB–512 MB | 8 KB | 4 KB | |
| 513 MB–1 GB | 16 KB | 1 KB | |
| 1 GB–2 GB | 32 KB | 2 KB | |
| 2 GB–4 GB | 64 KB | 4 KB | |
| 4 GB–8 GB | Not supported | ||
| 8 GB–16 GB | 8 KB | ||
| 16 GB–32 GB | 16 KB | ||
| 32 GB–2 TB | 32 KB |
I'm not sure why FAT16 partitions below 17MB have such large clusters, but I do suppose it's because they are really FAT12, not FAT16. FAT16 partitions larger than 2 GB are supported only by Windows NT/2000/XP, and therefore of little practical relevancy.
| Cluster Size | Maximum Partition Size | |
|---|---|---|
| MB | Bytes | |
| 2 KB | 127.98 | 134,197,248 |
| 4 KB | 255.96 | 268,394,496 |
| 8 KB | 511.92 | 536,788,992 |
| 16 KB | 1,023.84 | 1,073,577,984 |
| 32 KB | 2,047.69 | 2,147,155,968 |
The main question, of course, is, does it make sense to partition a harddrive to reduce slack? In most cases, I'd say no. A noteable exception might be if a harddisk is just above a limit, for example 1.2 GB. In this case, creating one partition under 1 GB and one under 256 MB might make a lot of sense.