What is the longest file path that Windows can handle?

Ron Tuffin

Posted 2009-07-29T08:06:18.240

Reputation: 2 390

Answers

In the Windows API (with some exceptions discussed in the following paragraphs), the maximum length for a path is MAX_PATH, which is defined as 260 characters. A local path is structured in the following order: drive letter, colon, backslash, components separated by backslashes, and a terminating null character. For example, the maximum path on drive D is "D:\<some 256 character path string><NUL>" where "<NUL>" represents the invisible terminating null character for the current system codepage. (The characters < > are used here for visual clarity and cannot be part of a valid path string.)

Adam Matan

Posted 2009-07-29T08:06:18.240

Reputation: 5 930

4You should mention that you can handle paths that exceed this limit by prefixing it with \\?\ (I think it was that character sequence). – Joey – 2009-07-29T08:54:45.817

3you should also state the limit for unicode-paths mentioned in the 2nd paragraph: ~32k – akira – 2009-09-28T15:29:33.930

@Phoshi The APIs to use longer paths aren't used by the OS by default, because passing in arbitarily long strings to applications that were poorly written by developers who knew the path could never be longer than 260 chars and decided to allocate a fixed length array to hold it would result in a huge number of buffer overflows leading to applications crashing and/or being exploited. Slightly better implementations by devs with the same mis-knowledge would abort because their path validation reported a too long error. – Dan is Fiddling by Firelight – 2012-05-25T15:45:25.843

260? 256 characters ignoring drive:\ and terminator. It's 2009, why do we only get a byte of characters to play around with? – Phoshi – 2009-10-11T16:57:02.647

XP file path- 250 characters

Vista file path - 260 characters

The longest path on a clean install of Windows XP is 152 characters.

The longest path on a semi-clean install of Windows Vista is 195 characters:

Windows XP allows file names upto 255 characters in length

Windows Vista allows even longer filenames containing upto 260 characters.

http://www.codinghorror.com/blog/archives/000729.html

joe

Posted 2009-07-29T08:06:18.240

Reputation: 11 615

this is incorrect. The maximum filename length is still 255 characters in any Windows, since that's the NTFS limit – phuclv – 2018-08-08T04:31:19.763

this is just true if you dont use the unicode-api, which extends the limit a bit (~32k, see http://msdn.microsoft.com/en-us/library/aa365247%28VS.85%29.aspx#maximum%5Fpath%5Flength)

– akira – 2009-09-28T15:30:44.427

1hmmm. at that rate, the limit in Win7 ought to be around 265 characters, no? – quack quixote – 2009-10-11T16:54:04.930

Why would they increase the limit by ten characters? Doesn't seem worth it, does it :\ – Phoshi – 2009-10-11T16:57:48.183

Windows constant MAX_PATH is equal to 260 as other answers says, however, real longest path is 32767.

See here.

32k is while using UNICODE, but now we must use it, so we should also use such max path length.

Also, you can take a look into my answer in SO which explains some things more detailed about maximum path length.

ST3

Posted 2009-07-29T08:06:18.240

Reputation: 615

The "classic" limit is 260 characters: drive letter + :\ + 255 characters of filename + \ (or for rounding) + null terminator as said in the other answers

However the real internal limit is 32767 characters which can be achieved by appending \\?\ to get a fully qualified path

The Windows API has many functions that also have Unicode versions to permit an extended-length path for a maximum total path length of 32,767 characters. This type of path is composed of components separated by backslashes, each up to the value returned in the lpMaximumComponentLength parameter of the GetVolumeInformation function (this value is commonly 255 characters). To specify an extended-length path, use the "\\?\" prefix. For example, "\\?\D:\very long path".

If due to some reasons the fully-qualified paths cannot be used then deeper directories can be accessed by mounting to a drive letter with subst/diskpart or by creating a junction/symlink to shorten the path

Since Windows 10 the MAX_PATH limit has also been removed although not by default

Starting in Windows 10, version 1607, MAX_PATH limitations have been removed from common Win32 file and directory functions. However, you must opt-in to the new behavior.

https://docs.microsoft.com/en-us/windows/desktop/FileIO/naming-a-file

phuclv

Posted 2009-07-29T08:06:18.240

Reputation: 14 930