Assembling the Avengers to save the universe carries a hefty price tag.

In a recent interview with Sway's Universe, Avengers: Infinity War co-directors Joe and Anthony Russo broke down the budget for the Marvel Studios production, which, at more than $300 million, is among the most expensive movies of all time. Joe Russo revealed that, at times, the cost to film Infinity War and Avengers 4 back-to-back cost upward of $450,000 daily.

RELATED: Which Infinity War Casualties Will Stay Dead in Avengers 4 (and Why)

"[We] shot for a year straight, from January to January, with about two weeks in-between," he said, before revealing that the back-to-schedule cost "350, 400, 450,000 a day just to keep the production running."

When asked what drove up the combined films' budget to a reported $1 billion, Anthony Russo joked that most of it went toward Robert Downey Jr.'s salary.

"It does break down that way where the cast does get a big percentage of it," Joe Russo elaborated. "These movies have been incredibly successful, there’s 18 of them, and typically as movies succeed, the cast can get more expensive. The VFX are incredibly expensive on a movie like this, well into the hundreds of millions. So between those two, those are the largest categories that take most of the money. Then there’s just the day-to-day running of a production that can be very expensive."

RELATED: Avengers: Infinity War Directors Discuss That Surprise Cameo

Despite the enormous budget, Anthony Russo admitted the production went over what was planned. "The irony is like no matter how much money you have, at some point you run out of money. So it’s pretty crazy," he said.

With Avengers: Infinity War having become the fastest film to reach $1 billion at the box office, it seems like Marvel Studios is at least well on its way to earning back its money.

Directed by Joe and Anthony Russo, Avengers: Infinity War stars Robert Downey Jr., Chris Evans, Chris Hemsworth, Mark Ruffalo, Jeremy Renner, Scarlett Johansson, Anthony Mackie, Paul Rudd, Elizabeth Olsen, Tom Holland, Benedict Cumberbatch, Chadwick Boseman, Chris Pratt, Zoe Saldana, Dave Bautista, Bradley Cooper, Vin Diesel, Tom Hiddleston, and Josh Brolin. The film is out in theaters everywhere.