Lifespan

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.

With Generations or patch 22, the length of each life stage can be adjusted individually. The length ranges from the Short lifespan to Epic:
 * 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) 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.

Lifespan Multiplier
Several life states have extended length of lifespan. These life states have lifespan multiplier that multiplies the default length of their age, but it only affects 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 2x multiplier on their age.