An ordinary annuity pays at the end of each period. Enter your payment, rate, term and frequency to see what those end-of-period payments grow into over time.
An ordinary annuity is a series of equal payments made at the end of each period — the end of every month, quarter or year. Its future value is what that whole stream of payments grows into once each one has earned compound interest through to the end of the term. The earliest payments compound the longest and contribute the most, which is why the final total dwarfs the sum of the payments themselves.
End-of-period timing is the standard convention, which is exactly why it is called “ordinary.” If your payments instead arrive at the start of each period, that is an annuity due and grows slightly more — you can switch to it on the general future value of annuity calculator. To layer these payments on top of an opening lump sum, use the future value calculator.
The only thing that separates an ordinary annuity from an annuity due is when each payment is made:
Because ordinary payments arrive later within each period, an ordinary annuity always ends up a little smaller than the equivalent annuity due. Over 20 years, $500 a month reaches about $260,463 as an ordinary annuity versus about $261,983 as an annuity due — a difference of roughly $1,500 that comes purely from timing.
Four inputs define the result, all assuming end-of-period payments:
The result splits the future value into what you paid in and the interest earned on top, and the year-by-year breakdown shows the balance building period after period.
The future value of an ordinary annuity is:
where PMT is the payment per period, i is the periodic interest rate (the annual rate divided by the number of periods per year), and n is the total number of payments. The term in brackets is the ordinary annuity factor — it sums up the growth of every individual payment into one multiplier, with each payment compounding for one period less than the payment before it. An annuity due simply multiplies this result by an extra (1 + i). The single-sum version this builds on is covered in the future value formula guide.
Here is how $500 paid at the end of every month grows as an ordinary annuity at 7 percent, compounded monthly, over different terms. The interest portion overtakes the payments as the term lengthens.
| Term | Future value | Paid in | Interest earned |
|---|---|---|---|
| 10 years | $86,542 | $60,000 | $26,542 |
| 20 years | $260,463 | $120,000 | $140,463 |
| 30 years | $609,985 | $180,000 | $429,985 |
Over 30 years the $180,000 you pay in becomes about $609,985 — more than two-thirds of the final balance is interest, all from letting each end-of-period payment compound for the years that follow.
End-of-period payments are everywhere in personal finance, which is why the ordinary annuity is the default case:
Whenever the money moves at the close of the period rather than the start, the ordinary annuity is the right model — and this calculator gives you the future value directly.
The concepts behind the numbers — read the full library in the Learn hub.
How regular monthly deposits grow over time, with tables by amount, rate and timeframe.
Guide · InvestingThe single-sum formula the ordinary annuity version is built on, variable by variable.
Guide · InvestingTurn a future goal into a monthly payment, the practical flip side of an annuity.
Guide · InvestingThe engine that makes each end-of-period payment grow, explained with examples.
Keep exploring — every tool below is free and works the same way.
The general version, with a toggle for ordinary or annuity-due (beginning-of-period) timing.
InvestingValue recurring payments plus an opening lump sum at a given interest rate.
InvestingProject what a single sum of money grows to, with a choice of compounding frequency.
InvestingConvert between present value and future value of money in either direction.
InvestingProject a portfolio's future value with regular contributions and compounding returns.
SavingsWatch a savings account grow over time with regular deposits and a chosen APY.