501 minutes (8 hours, 21 minutes).

While the season consists of 8 episodes—the same number as Season 1 but one fewer than Season 2—the episodes vary significantly in length. The season starts with standard 50-minute chapters and culminates in a massive, movie-length finale. Episode-by-Episode Breakdown

– 50 minutes Chapter Four: "The Sauna Test" – 53 minutes Chapter Five: "The Flayed" – 52 minutes Chapter Six: "E Pluribus Unum" – 60 minutes Chapter Seven: "The Bite" – 55 minutes

Approximately 8 hours and 7 minutes (487 minutes)

Here’s a deep report on the runtime of Stranger Things Season 3.

– 1 hour and 18 minutes Is Season 3 Longer Than Other Seasons?

Stranger Things Season 3: A Complete Breakdown of Runtime and Length