Netflix said 45 million subscriber accounts worldwide watched the Sandra Bullock thriller "Bird Box" during its first seven days on the service, the biggest first-week success of any movie made for the company's nearly 12-year-old streaming service.

Netflix, which typically refuses to provide viewership numbers, made the rare disclosure in a recent tweet as movie producers, writers, actors and investors continue to size up a company that has already reshaped the way the world watches video.

The first-week audience means nearly one-third of Netflix's 137 million subscribers watched the film from Dec. 21 through Dec. 27 — a holiday-season stretch when many people aren't working and have more free time. Had 45 million people actually gone to the theater to watch "Bird Box," it would have translated into about $400 million in box-office revenue, based on the current average price of a ticket.

But people were watching the movie on a service for which they already had paid and had the luxury of doing so without leaving their homes. That makes watching "Bird Box" more comparable to watching a television program, Wedbush Securities analyst Michael Pachter said.

By that yardstick, the viewership for "Bird Box" is less impressive. For instance, the Super Bowl typically attracts 100 million to 110 million viewers in the U.S. alone. The annual telecast of the Academy Awards has drawn a U.S. audience of 26 million to 40 million in recent years. And those totals are for a single day.

Television viewership and theatrical box-office numbers also are calculated by third-party firms, unlike the "Bird Box" figure released by Netflix. The Los Gatos, California, company has steadfastly refused to divulge its viewership because it regards the data as a competitive advantage in deciding what kind of programming will attract subscribers. All Netflix will say about its "Bird Box" number is that it counted only accounts that watched at least 70 percent of the film.