Predicting the Debate Ratings: Super Bowl? Nah. ‘Seinfeld’ Finale? Maybe.

It is hard to pinpoint how many Americans will tune in Tuesday night to watch the first and only scheduled debate between Vice President Kamala Harris and former President Donald J. Trump.

But here’s an educated guess.

First of all, this is not the Super Bowl. The N.F.L. championship game routinely draws north of 110 million viewers, essentially the high-water mark of live televised events. For the non-sporting crowd, the audience of 106 million people who watched the “M*A*S*H” finale in 1983 is nearly impossible to achieve in the era of smartphones and the internet.

But the “Seinfeld” finale? Not impossible.

The record for a presidential debate is 84 million viewers, for the first meeting in 2016 between Hillary Clinton and Mr. Trump. So Tuesday’s bout between Ms. Harris and Mr. Trump — which will be simulcast on nearly every major network — could theoretically draw an audience akin to the final episodes of “Seinfeld” (76.3 million) and “Cheers” (80 million).

Ratings-wise, the event has one factor in its favor: Mr. Trump, who has participated in three of the four most-watched general-election debates since 1976.

His first meeting with Joseph R. Biden Jr. in 2020 drew 73.1 million viewers, according to Nielsen, making it No. 3 on the list. His final meeting with Ms. Clinton in 2016 was seen by 71.6 million people, putting it at No. 4. (Both of those events, incidentally, were moderated by the anchor Chris Wallace. He is not moderating on Tuesday.)

The numbers from those events were all the more remarkable because they took place in the age of smartphones and streaming. Nielsen data mostly reflects a traditional TV audience; it does not encompass viewers who watch on YouTube livestreams or on a subscription app like HBO Max. (Those who watch on YouTube TV or Hulu Live, however, will be counted. It’s complicated.)