Investment Growth Calculator
Project investment growth over time with regular contributions.
Enter details to calculate investment growth.
What This Calculator Does
Most investing doesn't stop at a single deposit — it's an initial amount plus regular contributions added on top, month after month or year after year. This calculator models exactly that: start with a lump sum, add a recurring contribution on whatever schedule you choose, and let it grow at a chosen annual return rate over a set number of years. The result separates out how much of your ending balance came from your own contributions versus how much was earned as interest, alongside a year-by-year table of the whole trajectory.
How to Use It
Set your Initial Investment, Annual Return Rate, and Investment Period, then decide whether you want to add a Regular Contribution — it's optional, so leave it at zero to see pure lump-sum growth. Choose how often that contribution gets added (monthly or annually) and, separately, how often the return itself compounds, since the two don't have to match. The Projection Summary reports your Final Balance, Total Contributions, and Total Interest as three distinct figures, and the schedule table below shows the same breakdown for every year of the projection.
The Formula
The calculator simulates growth period by period rather than plugging into a single closed-form equation, but the underlying math matches the annuity-due future value formula: FV = P(1+i)ⁿ + C(1+i)[(1+i)ⁿ − 1]/i, where P is your initial principal, i is the rate per compounding period, n is the total number of compounding periods, and C is your contribution amount. It's annuity-due rather than ordinary annuity because each contribution is added to the balance at the start of its period and then compounds along with everything else already there, rather than being added at the end after that period's interest is credited — so your contributions earn interest starting immediately, not one period late.
A Worked Example
Start with $1,000, add $100 every month, at a 6% annual return compounded monthly, over 3 years. After 36 monthly contribution-and-compounding cycles, the calculator projects a final balance of $5,149.96. Of that, $3,600.00 is money you actually put in — the $1,000 initial deposit plus 36 payments of $100 — and the remaining $549.96 is interest the account earned along the way. That interest figure looks modest next to the contributions total mostly because three years isn't long enough for compounding to dominate the picture yet; stretch the same scenario out over a longer horizon and the interest share grows substantially faster than the contributions do.
FAQ
- What contribution frequencies are available?
- Monthly or annual contributions — choose what matches your investment schedule.
- Can I vary the expected return rate?
- Yes, enter any annual return percentage to project your growth. Results are shown as nominal returns, not adjusted for inflation.