The default order on almost any page on Letterboxd lists titles according to “film popularity.” But what defines a movie’s popularity? You might assume it’s determined by users’ scores on Letterboxd’s zero to five star scale. But it’s not; that determines a movie’s average rating, not its popularity.

It’s actually kind of hard to sort out what determines “popularity” on the site. Rooting around on Letterboxd doesn’t turn up an immediate answer. So here’s what Letterboxd itself has said.

According to Letterboxd’s social media team a couple years ago, a film’s popularity is determined by “a mix of member activity, including reviews, comments, watches, logs, watchlists, etc.”

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While Letterboxd didn‘t reveal the precisely formula used to calculate the numerical value they assign to a movie’s popularity, from that description it’s clear that “popularity” is really a measure of engagement; not just how much people like a movie (a simple star rating tells you that), but also how much people log it, review it, comment on it, add it to lists, and so on.

Popularity doesn’t necessarily imply a value judgment; if every person on Letterboxd was talking about a terrible movie, then it would still be very “popular” even though it was bad. Instead, think of it as an indication of interest. It tells you the movies people on the site are watching and talking about the most — and since you can sort popularity for different lengths of time (in a given week, month, year, or all time), you can track what films are the most discussed at various points.

As for the most popular movies in the history of Letterboxd, that’s easy to find: Just click the “Films” tab and sort the results for all time — all one million plus movies and shows contained in the app’s database. As of this writing the most popular film in history on the site is Greta Gerwig’s Barbie, which makes sense. The ten most popular films are (in this order)...

So there you have it; the most popular films on Letterboxd. Now go forth and log everything you watch with increased knowledge and insight.