When do you use "Cheers" instead of "Thank you" in spoken English?

A lot of time, people say "cheers" instead of "thank you". As I am not a native speaker, I wonder in which case you can use what.

It is used a lot for polite gestures, such as holding a door or giving someone a light. It is also more used if you know the person you are talking to.

Are there any rules?

The Macmillan Dictionary (American edition) says about cheers:

cheers, interjection : (British informal) thank you

In the US, thanks is the nearest informal equivalent. If you say "cheers" in the US, people will think you're offering a toast.

In countries that use British English, "cheers" is fine in the informal situations that you mention.

You can reserve "thank you" for more formal situations.

I think it varies a lot based on geography. In the US, "cheers" is rarely used to mean "thanks". In the UK, I can only really speak for my region (Midlands / Home counties), but we almost always say "cheers" as a laid-back replacement for "thanks". I'll say it the vast majority of the time instead.

Native Brit here from East Anglia. I use 'Cheers' when someone (a stranger) has done something nice. Like letting you get on a bus first, or holding a door open. I don't think there are any rules. It's just something I appropriated from other people. I tend to use thank you when buying something, or when the situation is a bit more formal, or with friends / family. I reserve cheers solely for using on strangers. I'm not very consistent though, I tend to use either whenever I feel like it. So defiantly no rules. I'd be interested to see what others say though.

I am a waiter in a restaurant. When I give a drink to an English guest, he thanks me by saying "Thank you" and my answer is "Cheers". Sometimes I get a reply "cheers for that". I'm using "Cheers" like a salute.