Investment Calculator

Project how an initial investment plus regular contributions could grow over time.

How this calculator works

This models monthly-compounded growth on your starting balance plus every recurring contribution, giving a realistic projection of a typical brokerage or index-fund investment.

A = P(1 + r/12)^(12t) + future value of monthly contributions
P = initial investment · r = annual return · t = years

Understanding investment risk

This calculator assumes a constant annual return for simplicity, but real markets fluctuate year to year. Treat the result as a long-term average projection, not a guarantee — higher expected returns generally come with higher volatility.

Frequently asked questions

Is 8% a realistic return assumption?

It's within the historical long-term range for diversified equity portfolios before inflation, but past performance doesn't guarantee future results.

How much difference do monthly contributions make?

A great deal over long periods — consistent contributions often account for more of the final balance than the initial investment itself, thanks to compounding.