We’ve heard an unconfirmed rumor that some people like to travel during the summer months, which is great; you need to get out more, enjoy life. But amid all that enjoying of life, don’t forget that you might not be able to access an in-network ATM for your bank account and could end up saddled with a bunch of no-fun fees.

To illustrate this point, the folks at NerdWallet looked at 20 of the nation’s biggest banks and the fees each bank charges for circumstances you might come up against when traveling to a town where people look at you funny when you mention the name of your bank.

There’s the standard out-of-network ATM fees that we all come up against when we absolutely need cash at the moment and don’t have time (or simply can’t be bothered) to find the nearest bank branch. About half the banks listed, including Bank of America, Citi, and Chase, charge $2.00 per transaction in this situation. Slightly fewer banks charge $2.50 per transaction; among these are Wells Fargo, PNC, HSBC, and TD Bank. Citizens Bank and M&T Bank charged the most for out-of-network ATM transactions, at $3 each.

More expensive are the fees charged by banks for using your card at an ATM internationally. A handful of banks — including Citi, Capital One, U.S. Bank, and HSBC — don’t charge higher fees just because the ATM is on international soil, but 11 of the 20 banks on the list jack up that fee to $5 per transaction. Worth noting is that Citizens Bank doesn’t charge a higher fee internationally, so its $3 out-of-network ATM fee is suddenly a bargain once you cross the border.

Of course, even those banks that don’t raise their ATM rates for using machines in other countries still charge a foreign transaction fee. All but four of the banks set that fee at 3%. KeyBank is only 1%, while Union Bank charges 2%. BBVA Compass charges 3% for purchases, but only 1% on ATM transactions. TD Bank is the only one on the list with no foreign transaction fee.

NerdWallet also looked at how likely you were to find an in-network ATM at a top travel destination. Wells Fargo and Chase topped that list, with 3,825 and 3,616 ATMs in these locations, respectively. Meanwhile, KeyBank had the fewest with only 230. What the number doesn’t show is how these ATMs are distributed among these destinations. For example, Chase may have hundreds of ATMs in Brooklyn and Manhattan, but there isn’t a single Chase ATM within 20 miles of center city Philadelphia.

So before you travel, see if your bank’s website has an ATM or branch locator. If so, do a quick check of your destination to see if you’ll be scrambling to find an in-network ATM.

If you’re traveling internationally, check with your bank to see if it’s part of any sort of international alliance that allows customers to use ATMs at certain foreign banks without being slammed by fees. NerdWallet points out that BofA is part of the Global ATM Alliance, which allows customers to withdraw from ATMs at banks like Barclays and Deutsche Bank without incurring additional fees (though a 1% foreign exchange fee will still apply).

For people who have time to switch financial institutions, a number of smaller banks and credit unions offer accounts with no out-of-network ATM fees, and online banks like Capital One 360 (nee ING Direct) don’t hit you with foreign transaction fees.

You can check out the full range of fees charged by the top 20 banks at NerdWallet.com.

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.