Even the best-communicating banks aren't as readable as "Moby Dick," according to the analysis, and they're a far cry from the Harry Potter book series. Banks with the least-readable sites rival an academic paper on chess — but are still light reading compared to the Harvard Law Review.

Bank websites are chock full of jargon and complex language that the typical customer doesn't find readable, according to a recent report from VisibleThread. The software company (whose services include readability analysis) analyzed the websites of 50 of the biggest U.S. banks, looking at metrics such a sentence length and ease of reading. They found that 58 percent of bank content is too complex for the typical customer.

You know you're in trouble when fictional Harry Potter spells like "expelliarmus" and "wingardium leviosa" are considered more understandable than the terms of your checking account.

"Several banks could improve their rankings by making simple changes," Fergal McGovern, CEO of VisibleThread, said in the report announcement. "Eliminate passive voice, reduce sentence length and choose less complex words."

In the meantime, it's up to consumers to work their own magic. (Sorry, spell casters, but "aparecium" probably won't cut it.)

Expect to do some digging and ask some pointed questions to make sure you understand the product or service you're signing up for, said Linda Sherry, director of national priorities for advocacy group Consumer-Action.

"You can't really get some of the information that you would prefer to have," said Sherry, who recently had to go on a hunt for what should have been an easy find: terms detailing the yield on her online savings account.

"We should know the cost of things, and what could possibly happen if we make a misstep," she said.

While the onus is on financial institutions to improve their language, it's also important for consumers to reach out to their bank if something is less than clear.

"We need to communicate when we don't find the information easily," she said.

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