ExpressionEngine® 3 User Guide

Legacy Documentation

You are using the documentation for version 3.5.17. Go here for the latest version or check here for your available upgrades to the latest version.

Add Sites to MSM

Each install of ExpressionEngine can power 1 site. Follow these steps to add more Sites to your ExpressionEngine installation.

Purchase Additional Sites

Pull up the manage purchases page in your account on (Make sure you’re logged into the same EllisLab account used to purchase the Multiple Site Manager license.) Next to the MSM license in question, you’ll see the option to Add Sites. Follow the checkout process in the store.

Download New License Key

After completing the order, head back to your manage purchases page and download your license key. You will need to upload the new license key before you can add your new sites.


There is no explicit limit on the number of MSM sites that can be installed on a single installation of ExpressionEngine. However, there is a technical limit on the size of your MySQL database table rows (see the MySQL documentation). This effectively limits the total number of custom channel fields, and thus ultimately the number of sites you can install. Depending on the types of fields and the MySQL storage engine, row size limits could pose a problem with anywhere between 500 - 2,000 custom fields. If you are concerned you may be using too many custom fields, our support team can help you decide whether more sites can be supported.