Here's how much it costs for a university to host a presidential debate

Thomson Reuters

Republican U.S. presidential nominee Donald Trump speaks as Democratic U.S. presidential nominee Hillary Clinton listens during their first presidential debate at Hofstra University.

Sunday night's presidential debate kicks off at 9 p.m. ET at Washington University in St. Louis, Missouri.

The whole affair will cost the university a ton of money - between $4 million and $5 million, to be exact. However, $2 million of that goes directly to the Commission on Presidential Debates, a representative for Washington University told KMOV.

The rest of the cost goes to things like security, crowd control, and providing the equipment and space necessary for the hordes of campaign operatives and journalists who descend on the campus.

Taylor Reveley, the president of Longwood University - which hosted the vice presidential debate on October 4 - told PBS that the entire affair cost the school around $5.5 million.

Reveley said that the money came from specifically earmarked fundraising, and not from students' tuition.

While hosting the debates is an expensive endeavor, for these universities, it's all about the pay-off in free advertising.

More than 80 million people watched the first presidential debate at Hofstra University, so it's a big opportunity for lesser-known universities to represent their brand.

Universities that have hosted presidential debates in the past estimate that it's equivalent to $45 million to $50 million dollars of advertising, as well as a huge opportunity for students to see the democratic process up close.

"The general election season is like a Super Bowl buy," Reveley said, per PBS.