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: 5x multiplier
- Vampire: 5x multiplier
- Unicorn: 3x multiplier (of horses)
- Genie: 2x multiplier
- Werewolf: 1.5x multiplier
- Fairy: 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.