Is there a limit to what a single folder or directory can hold?

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Summary: Hard disks continue to increase in size, as does what we're storing on them. There are limits, but not limits that most people need to worry about.

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There are limits, of course. The limit most people run into first is the size of their hard disk, but assuming that you have a big enough disk for everything, then other limits can come into play.

I will say this right away though: the size of the files in a single folder is not one of them.

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There's no practical limit on the combined sizes of all the files in a folder, though there may be limits on the number of files in a folder. More importantly, there are limits on individual file size that depend on what filesystem you're using on your hard disk. (The "filesystem" is nothing more than the specification of exactly how files are store on disk.)

Let's break this down by file system:

• FAT aka FAT16

  FAT, for File Allocation Table, is the successor to the original FAT12 filesystem that shipped with MS-DOS many, many years ago.

  • Maximum disk size: 4 gigabytes

  • Maximum file size: 4 gigabytes

  • Maximum number of files on disk: 65,517

  • Maximum number of files in a single folder: 512 (if I recall correctly, the root folder "/" had a lower limit of 128).

• FAT32

  "There's no practical limit on the combined sizes of all the files in a folder, though there may be limits on the number of files in a folder."

  FAT32 was introduced to overcome some of the limitations of FAT16.

  • Maximum disk size: 2 terabytes

  • Maximum file size: 4 gigabytes

  • Maximum number of files on disk: 268,435,437

  • Maximum number of files in a single folder: 65,534

• NTFS

  NTFS, or "New Technology File System" introduced with Windows NT, is a completely redesigned file system.

  • Maximum disk size: 256 terabytes

  • Maximum file size: 256 terabytes

  • Maximum number of files on disk: 4,294,967,295

  • Maximum number of files in a single folder: 4,294,967,295

Note that when I say "disk" above, I'm really talking about "logical" disks, not necessarily physical. No one makes a 256 terabyte disk drive, but using NTFS you can treat an array of disk drives as a single logical disk. Presumably if you have enough of them, you can build a huge logical drive.

Also note that the NTFS's 256 terabyte limitation may well simply be an implementation restriction - I've read that the NTFS format can support disks up to 16 exabytes (16 times 1,152,921,504,606,846,976 bytes).

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So there are two important take-aways from all that data as it relates to the original question:

1. Nowhere was there a limit of the size of the contents of a folder. Limits on the number of files, yes, but nothing size related.

2. You probably want to make sure your disk is formatted NTFS. FAT32's 4 gigabytes for a single file just isn't enough any more, especially if you're collecting video or other storage-intensive media.

Related:

• Ask Leo! - Can I adjust some master NTFS table size to handle large number of files better?

• Ask Leo! - Should I use Windows File Compression?

• Microsoft - A Brief and Incomplete History of FAT32

• Microsoft - Maximum Size Limitations

Article C3024 - May 14, 2007