Lifespan is the length of a Sim's age in each life stage, which also depends on their life state. Sims' lifespan can be set in the options menu of The Sims 3 that determines how long a Sim's natural life will be. As always, the Sim may die a premature, unnatural death, regardless of this setting.
The player can lengthen a Sim's lifespan in game without altering game settings by having them eat a Life Fruit (restores one day) or Ambrosia (resets days to age up), drink a Fountain of Youth Elixir (sets life stage to first day of young adult), become a Vegetarian or a creature like a mummy or a vampire, who live a number of days longer than a normal Sim.
- Short: ±25 Sim days
- Medium: ±50 Sim days
- Normal: ±90 Sim days
- Long: ±190 Sim days
- Epic: ±960 Sim days
Aging can also be turned off in the options menu to stop every Sim in town from aging. Drinking Age Freeze potion will disable aging of an individual Sim, regardless the aging option.
- Babies range from 1–65 days
- Toddlers range from 2–150 days
- Children range from 2–150 days
- Teen sims range from 3–300 days
- Young Adults range from 5–450 days
- Adults range from 5–450 days
- Elders range from 4–265 days
Pets (cats, dogs, horses)[TS3:P] also have their own lifespan, and like Sims, each of their life stage can be adjusted individually. Their lifespan option, however, is connected with Sims. If Sims have their lifespan set on Epic, the pets will also be in Epic lifespan.
Several life states have extended lifespans. These life states have a lifespan multiplier that multiplies the default length of their young adult and adult stages.
- Mummy[TS3:WA]: 5x multiplier
- Vampire[TS3:LN][TS3:SN]: 5x multiplier
- Unicorn[TS3:P]: 3x multiplier (of horses)
- Genie[TS3:ST]: 2x multiplier
- Werewolf[TS3:SN]: 1.5x multiplier
- Fairy[TS3:SN]: 5x multiplier
This means that when a Sim turns into a vampire, their age length in Normal lifespan as a young adult (previously 21) becomes 21 x 5 = 105 days. Additionally, Sims who wish for long life from a genie will get a 2x multiplier on their age.
- If the average real-world life span of 80 years is used in an equation, then it can be calculated that one day in The Sims 3 is equivalent to about 324 real-life days.
- One hour is 13.5 days and one minute is 5.4 hours.
- However, if Seasons was installed, a day in The Sims 3 has a varying equivalent of almost two days to a month in the real world depending on the user's settings.
- On an average setting, a year in the real world would be equivalent to 28 Sim days. This would make the "normal" lifetime of a Sim (90 Sim days) really short, stopping at around 3.21 years old, and the shortest possible lifespan (22 Sim days) being less than a year, equivalent to around 286.7805 real-life days.
- Making a Sim live at a maximum allowable lifespan (around 1928 Sim days on Epic setting), and shortening the year from Seasons (from an average of 28 Sim days to the minimum of 12 Sim days per year) would make a Sim live at a maximum lifespan of an astonishing 160 years, assuming this is not modified by any means such as consuming Ambrosia or turning into an another life state. On the other hand, the shortest possible lifespan, even with the 12-day minimum, would make a Sim live just under two years.