The length of the annuity varies depending on the terms chosen by the investor. Bankrate claims that annuity payouts may be calculated based on the total lump sum payment, growth rate and the time between withdrawals. The amount of money initially invested is paid back to the investor with an interest rate over a period of time.
As Bankrate reports, annuities have different beginning principles, growth rates and agreed term lengths. Annuities may end when the balance runs out or when the time period expires. Some annuities exist for the length of the investor's lifetime and end upon that individual's death. Other annuities provide payouts for a specific number of years at a fixed amount or percentage.
More frequent withdrawals, larger payout amounts and lower growth rates are likely to result in faster depletion of an annuity, according to Bankrate. Lifetime annuities last until the investor dies and often include an option to have payouts continue for a chosen beneficiary. These payments last a specific amount of time depending on the term chosen by the investor. Many investors choose this option to provide income for five, ten or fifteen years to a spouse or family member. The annuity ends after this time period expires.