The classic 1968 recording of Iron Butterfly’s “In-A-Gadda-Da-Vida” was about 17 minutes long.
The full album version runs slightly over 17 minutes—commonly listed at roughly 17:02 to 17:05—and occupies the entire second side of Iron Butterfly’s 1968 album of the same name. Its unusual length helped make it an emblem of psychedelic and acid rock, while its extended instrumental passages anticipated the long-form arrangements that became common in progressive and hard rock.
The recording includes a famous drum solo by Ron Bushy lasting about two and a half minutes, along with extended guitar and organ sections. The title itself is generally understood as a slurred version of “In the Garden of Eden,” reportedly heard during a sound check and written down by Bushy. The album was released in June 1968 and became a major commercial success.
The answer can cause confusion because the song was also edited for a 45-rpm single. That radio version lasts only about 2 minutes and 52 seconds. The question refers to the famous full-length 1968 recording, so “17 minutes” is the standard rounded answer; it is not asking for the shortened single.