Find what a starting amount plus regular deposits grows to at a rate you choose, with payments at the start or end of each period and the result in today's dollars
Enter a starting amount (present value), what you add each period, the annual rate, the number of years and how often it compounds. Choose whether deposits go in at the end of each period (an ordinary annuity) or at the start (an annuity due). The calculator splits the future value into growth on the starting amount and on the deposits, and shows it in today's dollars at the inflation rate you enter. The rate is your assumption; actual returns vary and investments can lose value.
With i = annual rate ÷ periods per year and N = years × periods per year: FV = PV × (1 + i)^N + PMT × ((1 + i)^N − 1) ÷ i. For deposits at the start of each period, multiply the second part by (1 + i). $5,000 plus $200 a month at 6% compounded monthly for 20 years: the $5,000 grows to $16,551, the deposits to $92,408, a future value of $108,959 from $53,000 put in. Depositing at the start of each month instead gives $109,421; depositing $2,400 once at the end of each year with annual compounding gives $104,321.
Prices rise, so a future balance buys less than the same number of dollars today. Real value = FV ÷ (1 + inflation)^years. At 2% inflation — the Federal Reserve's longer-run goal — $108,959 in 20 years is worth about $73,326 in today's money. The Bureau of Labor Statistics' Consumer Price Index (CPI) shows what inflation has actually been; enter your own estimate.
Dividing 72 by the annual rate estimates how many years money takes to double with compounding. The exact answer is ln 2 ÷ ln(1 + rate). The rule is close for rates between about 4% and 12%.
| Rate | Rule of 72 | Exact |
|---|---|---|
| 3% | 24.0 years | 23.4 years |
| 4% | 18.0 years | 17.7 years |
| 6% | 12.0 years | 11.9 years |
| 8% | 9.0 years | 9.0 years |
| 10% | 7.2 years | 7.3 years |
FV = PV × (1 + i)^N + PMT × ((1 + i)^N − 1) ÷ i, where i is the rate per period and N the number of periods. With no regular deposits it is just PV × (1 + i)^N.
At 6% a year compounded monthly, $108,959 — about $73,326 in today's dollars at 2% inflation. A different rate gives a different answer; returns aren't fixed.
An ordinary annuity pays at the end of each period; an annuity due pays at the start, so each deposit earns one more period of interest. In the example, that lifts the future value from $108,959 to $109,421.
Divide the future value by (1 + inflation)^years. At 2% for 20 years, every future dollar is worth about $0.67 today.
72 ÷ annual rate ≈ years to double. At 6% that is 12 years; the exact figure is 11.9 years.
Tax rules, limits and pay data change. Check the current figures with the primary source before acting on them.