Investment Return Calculator
Project the future value of your investments. Enter an initial amount, monthly contribution, annual return, and years to see growth with this free calculator.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Show the formula & steps
How the Investment Return Calculator Works
This calculator projects what your portfolio could be worth after years of regular investing. Enter your initial investment, a monthly contribution, an expected annual return, and a number of years, and it shows the future value, your total contributions, and the growth earned on top.
How it works
The future value combines a lump sum that compounds and a stream of monthly deposits that each compound for the time they are invested:
FV = P(1 + i)ⁿ + PMT × [((1 + i)ⁿ − 1) ÷ i]
where P is the initial amount, PMT is the monthly contribution, i is the annual return divided by 12, and n is the number of months (years × 12).
Worked Example
Start with $5,000, add $300/month, assume a 7% annual return, and invest for 20 years:
- Monthly rate i = 7% ÷ 12 = 0.5833%, months n = 240
- Future value ≈ $176,500
- Total contributed = 5,000 + 300 × 240 = $77,000
- Growth from returns ≈ $99,500
More than half of the ending balance comes from compounding, not from the money you put in.
How Time Drives Growth
| Years | Future value | Contributed | Growth |
|---|---|---|---|
| 10 | $61,974 | $41,000 | $20,974 |
| 20 | $176,472 | $77,000 | $99,472 |
| 30 | $406,574 | $113,000 | $293,574 |
(Initial $5,000, $300/month, 7% annual return.)
Getting the Most From Compounding
- Start early. Years in the market matter more than the size of any single contribution.
- Automate contributions. Steady monthly investing smooths out market ups and downs.
- Mind fees and inflation. Subtract fund fees from your return assumption, and remember that real spending power grows by return minus inflation.
Frequently asked questions
How do I calculate investment returns with monthly contributions?+
Combine two pieces: the future value of your starting amount, P(1+i)^n, and the future value of a stream of monthly deposits, PMT × [((1+i)^n − 1) ÷ i]. Here i is the monthly rate and n is the number of months. This tool does both for you.
What return rate should I assume?+
A diversified stock portfolio has historically averaged around 7% a year after inflation, while bonds are lower. Use 6% to 8% for a long-term stock-heavy plan, and lower for conservative portfolios. Returns are never guaranteed.
What is the difference between contributions and growth?+
Contributions are the money you put in: your initial amount plus every monthly deposit. Growth is everything the investment earns on top of that. Over long periods, growth can dwarf contributions thanks to compounding.
Does the calculator account for compounding?+
Yes. It compounds monthly, applying the monthly rate to your balance each month and adding your contribution. Monthly compounding closely matches how most brokerage and retirement accounts grow.
Is this the same as a compound interest calculator?+
It is closely related. A compound interest calculator usually grows a single lump sum, while this tool also adds regular monthly contributions, which is how most people actually invest over time.