WP_MEMORY_LIMIT

WP_MEMORY_LIMIT is the amount of memory WordPress asks PHP for on normal requests, such as the pages your visitors see. WordPress applies it right at the start: if the PHP memory limit is lower, WordPress tries to raise it to this value.

Why it matters

A request that runs out of memory stops with an error. WP_MEMORY_LIMIT lets WordPress give itself more room than the server’s default, for example on a site with a page builder or a shop.

It’s a request, not a guarantee. It works only if the hosting provider allows sites to change the memory limit. And it only ever raises the limit: if PHP already allows more, WordPress leaves it alone. Setting WP_MEMORY_LIMIT lower doesn’t make the site use less memory.

The admin area and other demanding tasks use a second, higher value: WP_MAX_MEMORY_LIMIT.

What influences it

WordPress: When nobody sets the value, WordPress uses a default. It can be set in wp-config.php, and some plugins and hosting providers set it there.

Server: Whether the value takes effect depends on PHP. When the provider has fixed the memory limit, WordPress can’t change it, whatever WP_MEMORY_LIMIT says.

In Permo

The Memory limit card is in System info, tab WordPress. It shows the value of WP_MEMORY_LIMIT, or No limit, and in the note the higher value for the admin area and background tasks, such as “Admin and background tasks: 256 MB”; see WP_MAX_MEMORY_LIMIT. If wp-config.php doesn’t set the constant, the card shows WordPress’s default. The card gives context; Permo doesn’t rate it.

What PHP actually allows, and how much of it a check used, is on the PHP memory card in the tab Server & System; see PHP memory limit.

Reference values

When the constant isn’t set, WordPress asks for 40 MB, or 64 MB on Multisite (source: developer.wordpress.org, wp_initial_constants(), accessed October 16, 2026).

Sources

WordPress: wp_initial_constants(), accessed October 16, 2026
WordPress: Editing wp-config.php, accessed October 16, 2026