Formula
FV = P(1 + R)^t + C × ((1 + r)^N − 1) ÷ r [× (1 + r) if paid at the start]r = (1 + R)^(1/m) − 1, N = m × t, m = contributions per yearReal value = FV ÷ (1 + inflation)^t How it works
This calculator projects what a portfolio could be worth if it earns a steady annual return. The expected return is treated as an effective yearly rate, and each contribution period gets the equivalent smaller rate, so monthly and yearly contributions are compared fairly.
Real markets do not deliver a smooth return. U.S. stocks have historically averaged roughly 9–10% a year before inflation, with large swings; a balanced stock-and-bond portfolio has averaged less. Many planners use 5–7% for long-term projections to stay on the conservative side.
The inflation-adjusted figure shows what the future balance would buy in today's prices. Over 20 or 30 years, even 2–3% inflation cuts purchasing power by a third or more, which is why real returns matter when planning for long-term goals.
Frequently asked questions
Does contributing at the start of the period make a big difference?
It adds one period of growth to every contribution. With monthly contributions the difference is small (about half a percent of the contributions' growth at 7%); with yearly contributions it is more noticeable.
Are fees and taxes included?
No. Subtract your fund's expense ratio from the expected return to account for fees — a 1% fee on a 7% return leaves 6%. Taxes depend on the account type; 401(k)s and IRAs defer or avoid them.
What return should I assume?
There is no right answer. Running the numbers at a low, middle and high rate (say 4%, 6% and 8%) shows a realistic range rather than a single precise-looking figure.