Proposal: Updating WP_MEMORY_LIMIT

During the Contributor Day at the WordCamp Europe 2022, the HostingHosting A web hosting service is a type of Internet hosting service that allows individuals and organizations to make their website accessible via the World Wide Web. Team found that WP_MEMORY_LIMIT is set as 40 MB (single site) and 64 MB (multisiteMultisite Multisite is a WordPress feature which allows users to create a network of sites on a single WordPress installation. Available since WordPress version 3.0, Multisite is a continuation of WPMU or WordPress Multiuser project. WordPress MultiUser project was discontinued and its features were included into WordPress core. Furthermore, the WP_MAX_MEMORY_LIMIT is set as 256 MB.

WP_MEMORY_LIMIT is the value for the WordPress Memory Limit, usually referred to the frontend memory, and WP_MAX_MEMORY_LIMIT is the value for the PHPPHP PHP (PHP: Hypertext Preprocessor) is a general-purpose scripting language especially suited to web development. PHP code is usually processed on a web server by a PHP interpreter. On a web server, the result of the interpreted and executed PHP code would form the whole or part of an HTTP response. Memory Limit, usually referred to the backend memory.


Around September 2013, the WP_MEMORY_LIMIT value changed from 32 MB to 40 MB (32+8). Some tests done by the Hosting Team suggest that the memory used on WordPress is around 16 MB.

The PHP memory_limit sets the maximum amount of memory in bytes that a script is allowed to allocate. This helps prevent poorly written scripts for eating up all available memory on a serverServer A server is a piece of computer hardware or software that provides functionality for other programs or devices. Typical servers are database servers, file servers, mail servers, print servers, web servers, game servers, and application servers.. Note that to have no memory limit, set this directive to -1. Check the PHP page for more information.

PHP values

The first part gets the value from PHP, and if not exists, sets a default value. Thereafter, if the value is incorrect (in bytes) sets the memory limit from the constant.

This PHP value has evolved:

Some questions

Why change the WP_MEMORY_LIMIT value?

To level it to the PHP standard.

If the hoster has some kind of limitation, misconfiguration, an incorrect value or does not allow changing it, the value used is the lesser, of 40 MB, which usually produces memory errors, when it should use the PHP default value, which is generally acceptable in new installations. At this time, 20 latest versions of WordPress (since WordPress 4.1 / 2014-12-17) can use PHP 5.6.40+ so it would meet the minimums set by PHP.

Can, actually, the value be greater than the PHP value?

Yes. That’s why there is an intent to include something like:



We should keep in mind some basic assumptions when incorporating PHP memory limits based on what users can do.

The memory limit set by computer systems are set for a reason. And that reason should be enforced; therefore, PHP’s memory limit should not be exceeded, and in case it needs to be exceeded, it should be changed by the system administration.

Users can set the values they want from the wp-config.phpwp-config.php One of the most important files in a WordPress installation is the wp-config.php file. This file is located in the root of your WordPress file directory and contains your website’s base configuration details, such as database connection information. configuration file. Often, extremely high values are set to hide a memory consumption problem due to bad programming. With a few visits it usually works, but it is a short-term fix.

We must be realistic about the memory limits of the WordPress CoreCore Core is the set of software required to run WordPress. The Core Team builds WordPress. and the normal use of a WordPress, whether it is a simple WordPress or a WordPress Multisite. Most WordPress sites install plugins and themes that make memory spikes higher.

PHP has its baseline memory limits that should serve as a reference for its use and application.


Considering that since 2008, and PHP >5.2.0 the memory_limit value is equal to 128 MB, should we consider an update of this value in the WordPress base configuration, or at least an update of the values?

The proposal from the WordPress Hosting team is for WP_MEMORY_LIMIT:

  • WordPress Single: define('WP_MEMORY_LIMIT', '128M');
  • WordPress Multisite: define('WP_MEMORY_LIMIT', '192M');

Another patch should be:


Users can modify the WP_MEMORY_LIMIT and WP_MAX_MEMORY_LIMIT at wp-config.php and should have some limitations in values, as far as WordPress cannot overflow PHP.

Getting the values

When doing some calls to PHP functions and values, got this:

  • php.iniphp.ini The main configuration file of PHP.: memory_limit -> value: 256M
  • function: memory_get_usage -> value: 2097152
  • updating the ini_set memory_limit to 512M -> value: memory_limit = 256M
  • function: ini_get_all[memory_limit]
Array (
  [global_value] => 256M
  [local_value] => 512M
  [access] => 7

So, the real values are, always, in the ini_get_all[memory_limit].

After doing some tests, maybe hard-coding the values is a bad idea, but having some “limits” is cool (like now) but reading the real values.

Ticket: 56390 Updating WP_MEMORY_LIMIT

Props: @javiercasares, @crixu, @bernardzijlstra, @mikeschroder.

#core, #performance, #php