Why are almost all anime episodes 20 minutes long?


Why are all animes around 20 minutes long? Sometimes less or more due to the
opening and ending, and some recap from last episodes...etc, but it's always
around 20 minutes.

Why is that?




Presumably it's to fit into the standard 30 minute time slot allocated for the
show.

  * 20 min. episode
  * [3 min. OP + ED (90 seconds each)](https://anime.stackexchange.com/questions/2597/when-and-why-did-the-trend-of-130-long-openings-and-endings-begin)
  * Commercials

And it's about 30 minutes.




Presumably it's to fit into the standard 30 minute time slot allocated for the
show.

  * 20 min. episode
  * [3 min. OP + ED (90 seconds each)](https://anime.stackexchange.com/questions/2597/when-and-why-did-the-trend-of-130-long-openings-and-endings-begin)
  * Commercials

And it's about 30 minutes.

