Project how a starting amount, expected return, and contributions could grow over time — computed in your browser, as estimates only.
Investment Calculator Online
Project how a starting amount, expected return, and contributions could grow over time — computed in your browser, as estimates only.
The Investment Calculator runs entirely in your browser. The amounts, rates, and years you enter never leave your device and nothing is uploaded to ArrayKit. Results are estimates only, not financial advice.
The Investment Calculator projects how a starting amount could grow given an expected annual return, a time horizon in years, and an optional yearly contribution added at the start or end of each year. Enter your starting amount, expected return percentage, and number of years, and it compounds the balance annually to show the ending amount, total contributions, and total growth split out separately. It is useful for sketching out a brokerage account, an index-fund position, or a general savings goal before you commit real money. Toggle the contribution timing to see how contributing earlier in the year changes the outcome. Everything runs locally in your browser — no financial figures are uploaded. These are estimates only and not financial advice; actual returns are never guaranteed.
Features
Solve for ending balance from a starting amount, return rate, and years
Optional yearly contribution added at the start or end of each year
Splits the result into end balance, total contributions, and total growth
Annual compounding using the standard growth formula
Copy a plain-text summary of every input and result
Clear error banner for negative or missing inputs
Runs entirely in your browser with no figures sent anywhere
Built-in reminder that projections are estimates, not guarantees
How to use the Investment Calculator
Enter your starting investment amount
Enter the expected annual return percentage
Enter the number of years to project
Optionally turn on a yearly contribution and choose start- or end-of-year timing
Read the end balance, total contributions, and total growth
Example
Input
$10,000, 7%, 20 yr
Output
End balance: $38,696.84
$10,000 growing at 7% annually for 20 years, with no added contributions.
Common errors & troubleshooting
The projected growth looks far too small. — Enter the return as a whole-number percent (7 for 7%), not a decimal fraction (0.07) — the Investment Calculator expects percent form.
Adding a contribution barely changes the end balance. — Confirm the 'Add a yearly contribution' toggle is on and the amount field is filled in; a blank or zero contribution has no effect.
Start-of-year and end-of-year timing give different totals for the same contribution. — This is expected — a start-of-year contribution compounds for one extra year, so it produces a slightly larger end balance.
The result assumes a steady annual return, but real markets are volatile. — Treat the output as a simplified projection at a constant rate. Real investments fluctuate year to year, so use the Investment Calculator for ballpark planning, not a guarantee.
Frequently asked questions
What does the Investment Calculator actually compute?
It projects an investment's ending balance using annual compounding: your starting amount grows by the expected return each year, with any yearly contribution added at the start or end of that year. It reports the end balance, total contributions, and total growth.
Does the Investment Calculator account for taxes or fees?
No. The Investment Calculator projects gross growth from your starting amount, return rate, and contributions only. It does not model taxes, account fees, or fund expense ratios — factor those in separately.
Is the projected return from the Investment Calculator guaranteed?
No. The Investment Calculator produces estimates only, not financial advice. It assumes a constant annual return you supply; real investment returns vary year to year and are never guaranteed.
Why does contribution timing change the Investment Calculator's result?
A contribution added at the start of the year earns a full year of growth before the next contribution, while an end-of-year contribution earns none until the following year — so start-of-year timing produces a larger end balance for the same amount.
Can I use the Investment Calculator for monthly contributions?
The Investment Calculator models one contribution per year. To approximate a monthly habit, multiply your monthly amount by 12 and enter that as the yearly contribution.
Does the Investment Calculator upload my financial figures?
No. The Investment Calculator runs entirely in your browser. The amounts you type never leave your device and are not uploaded to ArrayKit.
Related tools
Compound Interest Calculator — Project savings growth with compound interest and optional regular contributions.
ROI Calculator — Calculate return on investment, net gain and annualized ROI.