I started playing The Sims as the Facebook game The Sims Social back in 2011. Then I started playing The Sims 4 on July 20, 2017 while I'm also playing The Sims 3 again since December 18, 2017. Also take note that this user curses a lot on other wikis.
Having The Sims 3: Seasons installed and assuming a time duration of four seasons meaning one whole year, the following unmodified Lifespan results can be obtained:
The shortest life span available for a Sim is 24 real world days.
The longest life span available for a Sim is 160 real world years and 8 months (1928 Sim days divided by 12 Sim days per year)
A Sim day may fluctuate between roughly 2 real-life days to 1 month.