If your Sim is 16 sim days old, how old does that actually make them in human years? So I decided that I needed to come up some sort of rule regarding the length of a Sim year. Added to that some of the lengths of the age groups Baby, Toddler, etc. They also made the story-telling aspect of the move too quickly to be able to create any sort of meaningful life stories. After I came to understand the game better, I realized that these life-spans that I was playing were too short and did not allow for the time needed for my Sims to achieve their goals. So I came up with a custom lifespan of sim days that was in between the two. Then after playing with that for some time I came away thinking that Normal was too short and Long seemed too long. Yet after a while that was not working for me and I switched to the Long life-span of sim days. So, in the beginning I was going with the Normal life-span setting of 90 sim days. What I mean by that is that I wanted to get a number of generations into the game to see how the lives of my Sims would play out. When I first started playing The Sims 3 I was going for quantity, not quality.