I've read here, but I want to ask if I have understood this correctly.

We have a server in which WordPress admin needed more memory. The PHP memory_limit, in PHP.ini, is set to 256M, and so was WP_MAX_MEMORY_LIMIT in wp-includes/default-constants.php. There is a large amount of pages, and I think we will end up automatically delete pages that are older than a certain treshold, but as a quickfix I increased the memory.

I set the WP_MAX_MEMORY_LIMIT to 512M, and that works. The way I understood the documentation is that WordPress will be allowed to use 512M instead of PHPs memory_limit, which is set to 256M.

So, is it right that WP_MAX_MEMORY_LIMIT overrides PHPs memory_limit? It is able to use more memory than PHP is configured to use?

It certainly seems that way on our server now, but I want to be sure it is not something else going on.

EDIT: According to this answer, I can set the wp memory within the limit of php.inis limit. But that doesn't seem correct.


The true maximum is ultimately up to the host - they can impose whatever limits they wish. But even so, you can try with WP_MEMORY_LIMIT, which is the memory limit WordPress sets at runtime for any given request.

WP_MAX_MEMORY_LIMIT is only applied in certain situations, either for administrators in the backend (users with the capability manage_options), or for image resizing/other intensive operations.

  • I used WP_MAX_MEMORY_LIMIT because I only need this in admin mode :) But I am correct in saying that WP_MAX_MEMORY_LIMIT is the actual limit, as long as it is larger than memory_limit? – ptf Jul 12 '16 at 14:06
  • I also did an edit to the post at the bottom :) – ptf Jul 12 '16 at 14:08
  • WP_MAX_MEMORY_LIMIT is just a value (default 256M) that WordPress uses to ini_set( 'memory_limit' ) for administrators in the backend. If you want to know how exactly PHP handles memory, limits, INI files and runtime ini settings, you're much better off asking on Stackoverflow/PHP-specific channels. – TheDeadMedic Jul 12 '16 at 15:29

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