Maximum size of a PHP session

Solution 1:

You can store as much data as you like within in sessions. All sessions are stored on the server. The only limits you can reach is the maximum memory a script can consume at one time, which by default is 128MB.

(Similar answers: Ideal PHP Session Size? - some useful comments)

Solution 2:

This is limited by max file size of your operating system (if storing session to file) or column size (if storing session to database).

Using custom handlers, it is possible to have a session file that is greater in size than the amount set in memory_limit.

Therefore, it is a combination of max file/column size and memory limit.