Is there a limit to filename length?

I'm designing a database table which will hold filenames of uploaded files. What is the maximum length of a filename in NTFS as used by Windows XP or Vista?

asked Nov 5, 2008 at 16:39

GateKillerGateKiller

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It's 257 characters. To be precise: NTFS itself does impose a maximum filename-length of several thousand characters (around 30'000 something). However, Windows imposes a 260 maximum length for the Path+Filename. The drive+folder takes up at least 3 characters, so you end up with 257.

answered Nov 5, 2008 at 16:45

5

This is what the "Unhandled exception" says on framework 4.5 when trying to save a file with a long filename:

The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters.

Samuel Liew♦

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answered Apr 12, 2013 at 12:29

199 on Windows XP NTFS, I just checked.

This is not theory but from just trying on my laptop. There may be mitigating effects, but it physically won't let me make it bigger.

Is there some other setting limiting this, I wonder? Try it for yourself.

answered Nov 5, 2008 at 16:48

dovedove

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The length in NTFS is 255. The NameLength field in the NTFS $Filename attribute is a byte with no offset; this yields a range of 0-255.

The file name iself can be in different "namespaces". So far there are: POSIX, WIN32, DOS and (WIN32DOS - when a filename can be natively a DOS name). (Since the string has a length, it could contain \0 but that would yield to problems and is not in the namespaces above.)

Thus the name of a file or directory can be up to 255 characters. When specifying the full path under Windows, you need to prefix the path with \\?\ (or use \\?\UNC\server\share for UNC paths) to mark this path as an extended-length one (~32k characters). If your path is longer, you will have to set your working directory along the way (ugh - side effects due to the process-wide setting).

Jesper

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answered Aug 24, 2010 at 13:51

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According to MSDN, it's 260 characters. It includes "<NUL>" -the invisible terminating null character, so the actual length is 259.

But read the article, it's a bit more complicated.

answered Nov 5, 2008 at 16:42

KibbeeKibbee

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answered Nov 5, 2008 at 16:40

warrenwarren

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I'm adding this to the above approved answer.

TO BE CLEAR, the reason people believe it to be 255-260 characters is because that is all that Windows Explorer supports. It will error out doing something like a file copy on filenames longer than that. However, a program can read and write much longer filenames (which is how you get to lengths that Explorer complains about in the first place). Microsoft's "recommended fix" in situations like this is to open the file in the original program that wrote it and rename it.

answered Oct 9, 2012 at 14:16

2

This part of the official documentation says clearly that it’s 255 Unicode characters for NTFS, exFAT and FAT32, and 127 Unicode or 254 ASCII characters for UDF.

Apart from that, the maximum path name length is always 32,760 Unicode characters, with each path component no more than 255 characters.

answered Aug 9, 2018 at 20:31

cawcaw

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According to the new Windows SDK documentation (8.0) it seems that a new path limit is provided. There is a new set of path handling functions and an definition of PATHCCH_MAX_CCH like follows:

// max # of characters we support using the "\\?\" syntax
// (0x7FFF + 1 for NULL terminator)
#define PATHCCH_MAX_CCH             0x8000

answered Sep 11, 2013 at 17:19

1

255 chars, though the complete path should not be longer than that as well. There is a nice table over at Wikipedia about this: http://en.wikipedia.org/wiki/Filename.

answered Nov 5, 2008 at 16:44

Svante SvensonSvante Svenson

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In Windows 11 (In NTFS drive) is 236 with extension

For testing rename a file with below name and try to add one character more:

1234567890123456789010123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890.txt

answered Oct 21 at 4:59

MehdiMehdi

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238! I checked it under Win7 32 bit with the following bat script:

set "fname="
for /l %%i in (1, 1, 27) do @call :setname
@echo %fname%
for /l %%i in (1, 1, 100) do @call :check
goto :EOF
:setname
set "fname=%fname%_123456789"
goto :EOF
:check
set "fname=%fname:~0,-1%"
@echo xx>%fname%
if not exist %fname% goto :eof
dir /b
pause
goto :EOF

answered May 28, 2015 at 14:08

SzBSzB

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Actually it is 256, see File System Functionality Comparison, Limits.

To repeat a post on http://fixunix.com/microsoft-windows/30758-windows-xp-file-name-length-limit.html

"Assuming we're talking about NTFS and not FAT32, the "255 characters for path+file" is a limitation of Explorer, not the filesystem itself. NTFS supports paths up to 32,000 Unicode characters long, with each component up to 255 characters.

Explorer -and the Windows API- limits you to 260 characters for the path, which include drive letter, colon, separating slashes and a terminating null character. It's possible to read a longer path in Windows if you start it with a \\"

If you read the above posts you'll see there is a 5th thing you can be certain of: Finding at least one obstinate computer user!

user692942

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answered Nov 20, 2009 at 17:01

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I cannot create a file with the name+period+extnesion in WS 2012 Explorer longer than 224 characters. Don't shoot the messenger!

In the CMD of the same server I cannot create a longer than 235 character name:

The system cannot find the path specified.

The file with a 224 character name created in the Explorer cannot be opened in Notepad++ - it just comes up with a new file instead.

answered Feb 23, 2018 at 21:12

ajehajeh

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