If it's a 15 amp circuit it can handle up to 1650 watts. That's a lot of cell phones, IPads, etc that one can hook up. It's also best to keep your usage at around 80% of it's rated usage, so 1320 watts would be about right.
Here's good chart to get a GENERAL idea.
Funny thing on our last trip we were sitting at Margaritaville at MBJ and an electrical fire started at the top of the bar. It went out for about 15 seconds and the staff laughed it off. I asked if it happens often and was told "no mon, da first time."
Cracked me up.....