Find the Thai Baht Exchange rate on this page.
Thai Baht and Map
If you are going to bring US dollars to Thailand, make sure the notes are not torn, in reasonably "good condition" and do not bring any US 100 dollar bills in the 1990-1993 series. There were, and maybe there still are many forgeries of this particular U.S dollar series, and most or maybe all the banks and money changers will reject them.
The best place to exchange money for Thai baht is in Thailand. Will you be staying in Bangkok? I recommend giving yourself 1000 baht at the airport (in 100 baht bills) and then when you get to Bangkok you can trade the rest.
There's a place on 133 Sukhumvit Road with the best deal I've found in the Kingdom.
It's called Vasu exchange. You can trade in all major currencies and again...you can get a great deal.
I recommend that you have more smaller bills than larger ones. Most stores and shops in Thailand can't change 500 or 1000 baht bills. In fact most Thais create change for those by buying something at the 7-11.
If you can ask for smaller notes as often as possible. You'll also reduce your chances of getting ripped off. Many stores and taxi drivers will claim "oh, I don't have change." and you might be giving away more of your money than you'd like. Get more practical tips on having Thai currency on this link.
It's up to you.
Whatever happens once you're about to leave Thailand I recommend exchanging your Thai baht in the Kingdom. You can also leave your money in one of the Thai banks. Most foreign countries don't give a good exchange rate. What could be worse - many countries don't change Thai baht!
Keep tabs on the rate of the baht. It usually doesn't fluctuate from the rate you've seen above by more than 5%. That being said the trend for the last 5 years has been that it's getting stronger.
Find out more about banks in Thailand
Everything you need to know about exchanging money once you arrive
Thailand Practical Travel Information
All the advice you need before you arrive to the Land of Smiles
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