The anime "Demon Slayer" consists of several seasons and movies. As of now, there are 63 episodes in total, plus multiple movies. The upcoming "Demon Slayer: Kimetsu no Yaiba Infinity Castle Chapter 1" movie has a runtime of 2 hours and 35 minutes (155 minutes). The fourth season covered the Hashira Training arc in 8 episodes, and the earlier seasons and arcs have varying lengths, including a first season of 26 episodes and a second season of 18 episodes (including the Mugen Train arc and Entertainment District arc).
Overall, watching the entire series including seasons and movies would take over 20 hours, with individual movies like Infinity Castle running close to two and a half hours.
If a total runtime or episode count specifically is needed, it is around 63 episodes plus several movies, with new movies continuing the story in multiple parts.