Hi and welcome!
Where, specifically, do you mean by "overseas"? That pretty much encompasses most of the planet... but I'm going to take a wild leap of logic and guess that you mean (western) Europe.
Theoretically you could get by on very little if you managed to either mooch a lot or get an under the table job somewhere... but personally I would budget for at least $75 USD per day for a typical trip to Europe involving most of the bigger [read: expensive] cities. Some days you'll spend way less, some days you will spend more... and it's always a good idea to have a cushion. With the shitty exchange rate of the dollar to the Euro (and the pound), Europe is getting more and more expensive. Even just one year ago I would have said that $50/day US would be a bare-bones minimum, but now it's more like $75, really.