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.
