Why does Facebook say I'm online when I'm not?

[Lauren]

I have chat turned off on my computer and my phone, but my friends will still tell me the little green dot is next to my name, meaning I'm online. I know no one else is signed onto my account because I just changed my password and ended all active sessions. What else could be causing it to say I'm online?
I don't use the mobile app, but I do log in on safari. I have to log out of the Facebook website on safari and it won't show me as being online?

[Blaze]

Same problem... I'm guessing it's to do with the fact that I've logged in on my phones and sync is on... I don't really mind, just ignore people you don't like...

[Harry_with_cam]

When ever we logged in from mobile devices Facebook will always shows that you are online. Even if internet is not connected. So you have to log out first from your mobile device then it will not show you online.

[thatdude]

The other person's answer is probably the case but it may be because your friends haven't refreshed their app or facebook page in a while, causing chat to reload.