The film stars Zoe Kazan and Michael Stahl-David. Whedon penned and produced it.
The release will be the second film release for Whedon's "micro studio" Bellwether Productions, following last year's adaptation of Shakespeare's "Much Ado About Nothing."
Whedon has experimented previously with digital releases. His 2008 miniseries "Dr. Horrible's Sing-Along Blog" was among the first high-profile Web series.
Whedon currently is working on the "Avengers" sequel "Age of Ultron," to be released next year.
Nas' 'Time Is Illmatic': An Inside Look At the Tribeca Film Fest Premiere, Concert
The movie maker’s campaign has echoes of Radiohead’s 2007 experimental release of “In Rainbows”. The leftfield British band initially made the studio set available through its own Web site, allowing downloaders to set their own price. And the average price fans paid for the album? Many cite a figure around $5.
“In Rainbows” was an international chart hit when it was later released through traditional channels.