The American version of Big Brother typically lasts about 82 to 100 days, which is roughly 12 to 14 weeks. For example, Big Brother 25 lasted about 100 days, while Big Brother 24 was 82 days long. The current season, Big Brother 27, has a filming duration of around 83 days, which is approximately 12 weeks.

The British version varied but often lasted around 77 to 94 days, roughly 11 to 13 weeks depending on the season.

In general, Big Brother seasons run for about three months or 12 to 14 weeks.