Future Value Calculator · Practical guide
Future Value Calculator with Monthly Contributions
Combine a starting balance with steady monthly deposits and see exactly how compounding splits your growth.
At a glance
What This Calculator Shows
This future value calculator projects an investment that grows with monthly compounding plus monthly contributions. Enter a present value, an annual return rate, a number of years, and a monthly contribution, and it reports three numbers: the future value, your total contributions, and the total interest earned — so you can see how much of the final balance is your money versus growth.
Interactive tool
Future Value Calculator
Enter your own values, then compare the result with the examples below.
Future Value Projection
A Worked Example
Start with $10,000, add $500 at the end of every month, earn 6% compounded monthly, and wait 20 years:
- Future value: $264,122
- Total contributions: $120,000 (plus the $10,000 start = $130,000 paid in)
- Interest earned: $134,122
More than half the final balance is pure compounding.
The Formula Behind It
FV = PV × (1 + r)^n + PMT × ((1 + r)^n − 1) / r
Here r is the annual rate divided by 12, and n is years times 12. The first term grows your starting balance; the second grows the stream of monthly deposits. Contributions land at the end of each month, so the final deposit earns no interest — matching how most automatic investment plans actually work.
Starting Balance vs Monthly Contributions
Which matters more depends on the horizon. Over 20 years at 6%:
- $10,000 alone grows to $33,102 — interest of $23,102.
- $500 a month alone grows to $231,020 — interest of $111,020 on $120,000 contributed.
For most savers, the monthly habit does the heavy lifting; the lump sum is a bonus.
Common Uses
- Retirement savings projections (for employer matching, a dedicated 401(k) calculator fits better).
- College savings for a child, starting from a gift balance.
- Building a house down payment fund from monthly deposits.
Frequently Asked Questions
What if I make no monthly contributions?
Enter zero in the contribution field. The calculator then projects pure compound growth on your present value — for example, $10,000 at 6% for 20 years becomes about $33,102.
Does it compound monthly or annually?
Monthly. The annual rate is divided by 12 and applied each month, with contributions added at the end of each month. Monthly compounding produces slightly higher results than annual compounding at the same stated rate.
Is the result adjusted for inflation?
No — the output is in nominal dollars. To approximate real purchasing power, rerun the calculation using your expected return minus the inflation rate.
Can I use a negative contribution to model withdrawals?
The tool is designed for accumulation and accepts zero or positive contributions. For drawdown planning, project the balance at retirement first, then use a withdrawal calculator.