Investment

Compound Interest Calculator

Estimate growth from an initial investment and monthly contributions.

Results

A clear summary of your calculation.

Enter values and press Calculate to see an explanation.

INTERPRETATION

The final value combines your contributions and compounded return. A fixed return is illustrative; market returns vary.

FORMULA

FV = PV {(1 + \frac{r}{m})}^{m t} + \sum_{j = 1}^{12 t} PMT {(1 + \frac{r}{m})}^{\frac{(12 t - j) m}{12}}

Final value equals the compounded initial principal plus the accumulated value of each monthly contribution.

WORKED EXAMPLE

Enter an initial investment of 100,000 and a monthly contribution of 5,000.
Set a 7% annual return, 10 years, and monthly compounding.
The result separates 700,000 of contributions from the modeled investment gain and final value.

When are monthly contributions added?

At month end, so the new contribution earns no interest for that month.

Is the annual return guaranteed?

No. The calculator uses a constant assumption and cannot predict market fluctuations.

What changes with compounding frequency?

At the same nominal annual rate, more frequent compounding generally raises the effective annual return.

Convert growth over a period into an equivalent annual rate.

Value future cash flows today using a chosen discount rate.