How large is HTML5 session storage?

Although the size of localStorage has been addressed in detail and there is a online test for it, I was wondering what the maximum size of sessionStorage is for the common browsers?

According to this site, Firefox’s and Safari’s storage limit is 5MB per domain, Internet Explorer’s limit is 10 MB per domain.

However, according to this site which tests your web browser local storage capabilities, on my machine:

Browser        LocalStorage         SessionStorage
-------        ------------         --------------
Chrome              5M                   5M
Firefox             5M                Unlimited
IE11                5M                   5M

Also, note the handy chart at the bottom of the page.