Investment Growth Calculator With Monthly Contributions
Estimate a hypothetical future value from a starting amount, monthly contributions, an assumed annual return, and a time period. This is an illustration—not a market forecast, guaranteed balance, or recommendation to invest.
Enter zero or a positive amount for investments, contributions, and return, plus a period greater than zero. Results are unavailable until the inputs are valid.
Calculator results
Illustrative Return Scenarios
Future Value
$0
Total Contributions
$0
Modeled Gain
$0
Ending Value ÷ Contributions
0x
Average Modeled Gain per Year
$0
Investment Breakdown
Year-by-Year Growth
| Year | Contributions | Modeled Gain | Balance |
|---|
How this investment growth calculator works
The investment growth calculator estimates a hypothetical future value from a starting amount, monthly contributions, an assumed annual return, and a selected period. Change the inputs to compare arithmetic scenarios. The result is not a market forecast, a guaranteed balance, or a recommendation to invest.
For this projection, the nominal annual rate is divided by 12. The calculator applies that same monthly rate to the existing balance, then adds the contribution at the end of the month. This fixed-rate method is a simplification; actual investment returns vary and can be negative.
What the results mean
- Projected future value: the modeled balance at the end of the selected period under the inputs shown.
- Total contributions: the starting amount plus the monthly deposits entered for the selected period.
- Modeled gain: projected future value minus total contributions. It is not bank interest, realized investment profit, or annualized performance.
- Ending value ÷ contributions: a ratio comparing projected ending value with all modeled deposits, not an investment-return percentage.
- Average modeled gain per year: total modeled gain divided by the selected years, not an annualized return.
Example: investment growth with monthly contributions
For an illustration, enter $10,000 as the starting amount, $500 per month, 20 years, and an assumed annual rate of 8%. With monthly compounding and end-of-month contributions, the model gives a future value of about $343,778. Total contributions are $130,000, so modeled gain is about $213,778. The 8% value is an example input only—not an expected return, forecast, or recommendation.
Formula used
Future value = P × (1 + i)n + C × ((1 + i)n − 1) ÷ i
P is the starting amount, C is the monthly contribution, i is the assumed annual rate as a decimal divided by 12, and n is the number of monthly periods. If i is zero, future value is P + (C × n). This describes the calculator’s simplified scenario, not the path or risk of an actual investment.
What this estimate leaves out
This projection does not model changing returns, market volatility, losses, sequence-of-returns risk, inflation, taxes, fees, fund expenses, trading costs, contribution limits, or withdrawals. It is nominal and does not show future purchasing power. Investor.gov explains investment risk, including uncertainty and potential financial loss.
For comparison, Investor.gov provides a compound interest calculator. Tools can use different compounding and contribution assumptions, so compare those assumptions before interpreting differences.
Related tools include the Savings Goal Calculator, Net Worth Calculator, and Budget Planner.
Educational information only. This calculator provides a mathematical illustration, not individualized financial, tax, or investment advice.
Frequently Asked Questions
No. It calculates a hypothetical value from your inputs and a fixed-rate assumption. It does not forecast market performance or the probability of reaching the displayed amount. Actual investments can fluctuate and lose value.
It is projected future value minus the starting amount and modeled contributions. It is not guaranteed interest, a realized gain, or annualized investment performance.
There is no single rate this page can recommend for every investment or person. Treat the rate as an assumption for a scenario, not a prediction. This calculator does not assess risk tolerance or recommend an asset allocation.
Tools may use different compounding intervals, contribution timing, fees, taxes, or rounding. Check those assumptions before comparing results.
No. The result is nominal and excludes inflation, taxes, fees, and other costs. It should not be interpreted as spendable future purchasing power or an account statement.
Not in this calculator. It models a future value with recurring contributions. The difference between projected value and total contributions is not a formal or annualized return measure.