How many seasons does The Big Bang Theory have?

How to get close to this number

This is at the top of the network sitcom range, so anchor on the other sitcoms here and adjust upward. Nine and ten are typical for hits; twelve means a show that kept its ratings unusually long, which is exactly what happened.

Twelve seasons of a multi-camera sitcom is somewhere over two hundred and seventy episodes, which is why the format matters more than the season count. Multi-camera shows are filmed on standing sets before a live audience, which makes them far cheaper per episode than single-camera comedy — and cheap episodes are what allow a run this long.

The prequel spinoff in the explanation is the commercial logic of a franchise rather than a story: a successful sitcom generates a property, and the property outlives the show. Television companies now plan for that from the start, which is why season counts for individual series understate how long a set of characters actually stays on air.