Investment Calculator - Growth with Monthly Contributions

Investment Growth Calculator

Project how an investment grows when you combine a starting lump sum with steady monthly contributions. The calculator compounds monthly, mirrors how most brokerage and index-fund accounts actually accrue returns, and shows the final value, everything you put in, and the growth your money generated. All math runs locally in your browser with no sign-up.

Long-term investors, first-time savers, and financial coaches use this kind of projection to set expectations before opening a brokerage account or increasing an automatic transfer. It answers the practical question: if I start with X and add Y every month, what could I have in 10, 20, or 30 years at a given return?

Each month the calculator adds your contribution and then applies one twelfth of the annual return, so contributions made early in the period earn far more than those made near the end. That sequencing is why doubling your time horizon usually beats doubling your monthly amount: compounding needs years to do its heaviest lifting.

As a reference point, a 10,000 lump sum plus 500 per month at a 7% annual return grows to roughly 302,000 after 20 years, of which about 172,000 is growth. Historical broad stock-market returns have averaged 7-10% per year before inflation over long periods, but any single decade can differ sharply, so treat the rate as an assumption, not a promise.

For a pure lump-sum projection try our Compound Interest Calculator, and if you invest a fixed amount every month without a starting sum, the SIP Calculator models exactly that pattern. Both are free browser tools on ToolForte.