Updated June 20, 2026
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See how a single balance grows on its own with the Compound Interest Calculator, no monthly contribution required.
How the future value is calculated
Future value = the grown starting amount plus the grown stream of contributions. The starting amount follows FV = P(1 + r/n)^(nt), where P is the initial amount, r is the annual return, n is the number of compounding periods per year, and t is the number of years. Each monthly contribution is treated as its own deposit that compounds for the time it stays invested, and the calculator sums them all.
A year-by-year view
It helps to picture the path rather than the endpoint. With a $10,000 start, $500 invested monthly, and a 7 percent annual return, the balance climbs steadily, and the yearly gains get larger because each year compounds on a bigger base. The first year adds roughly your contributions plus a modest return; a year near the end can add more in growth alone than you contribute. Lengthening the timeline or raising the monthly amount usually changes the final figure more than a small bump in the assumed return.
Reading the result honestly
The future value is a nominal, pre-tax estimate built on one fixed return. Real markets do not deliver the same percentage every year, and inflation lowers what a future dollar buys. Treat the number as a planning anchor, not a promise. For plain-language basics on investing and compounding, the U.S. Securities and Exchange Commission publishes free guidance at investor.gov.
This tool is informational and educational. It is not financial or investment advice, and investing involves risk, including possible loss of principal.
A reformed credit analyst, Jessica Martinez turns dense financial paperwork into something you can actually use. She writes the explainers behind these calculators and checks every formula against a primary source before it ships.