How this calculator works
Your starting balance earns interest each month. Contributions are added at the end of each month, so earlier deposits have more time to grow. The chart shows each year-end balance, including your contributions.
FV = P(1 + r)ⁿ + C × ((1 + r)ⁿ − 1) / rP = starting amount; C = monthly contribution; G = target; r = monthly rate; n = months; y = years, where applicable.
Example you can check
With $1,000 invested, no contributions and a 12% nominal annual rate, one year of monthly compounding gives $1,126.83.
Assumptions & limitations
The annual rate is a nominal rate divided by 12. Growth compounds monthly at a constant rate; contributions arrive at month-end. Taxes, fees and inflation are excluded. Investment returns fluctuate and are not guaranteed.
Common questions
Is this an investment forecast?
No. This is a scenario using your chosen constant rate. Compare several rates and account for fees and inflation before making a decision.
When are contributions added?
At the end of every month. Beginning-of-month contributions would earn slightly more interest.
Further reading: investor.gov educational guide. Our formula conventions and examples are described above.