I'm switching a single WordPress site to a WordPress Multisite. I'm maintaining some post meta boxes with custom fields, and some front-end forms, where I maintained some features like maximum upload size for media library uploads, and restricted to some specific file types, using some third party plugins.

While switching to multisite, I noticed that the features are implemented by core per blog. I loved that. As it's functioning properly, I need to get those value from database, so that I can warn my users about the accepted file types and maximum upload limit per file in a tooltip or in an instruction field.

I know I can do this easily using $wpdb, but is there any default functions, that can facilitate me fetching the data easily?

1 Answer 1


Yes, you can easily grab those multisite values from database using an MU (μ) Function: get_site_option()

Getting Fields

Maximum Upload Size

The maximum upload size, per site (NOT per blog), per file can be found using:

$max_up = get_site_option('fileupload_maxk');
var_dump($max_up); //in kilobytes

Accepted File Types

The accepted file types per site (NOT per blog) can be found using:

$aft = get_site_option('upload_filetypes');
var_dump($aft); //space separated values

//values in an array :)
$aft_array = explode( ' ', $aft );

Under the hood

The values are stored in WordPress multisite database, in sitemeta (can be wp_sitemeta) table, just like any other meta table, using a meta_id, meta_key and meta_value. But as it's site specific (NOT blog specific), so the site_id is also stored.

Why site_id? Please refer to the #3 link of References.


  1. MU (μ) Functions - WordPress Codex
  2. get_site_option() - WordPress Codex - for additional $keys
  3. Wordpress: difference between site_id and blog_id? - StackOverflow

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