Episode 11 of The Summer I Turned Pretty (TSITP) Season 3 is expected to be longer than most episodes, possibly even a "movie-length" finale, although the exact runtime has not been officially confirmed by Prime Video. Most TSITP episodes run close to an hour, with some going beyond that in Season 3, so anticipation is for an extended finale possibly over an hour. This episode will be the finale, airing on September 17, 2025.
In summary: The episode length is likely around or over an hour, potentially longer than usual as a finale, but exact duration details will only be clear once it airs or official info is released.
