Investment Calculator
ROI & growth projections
Investment Calculator tool
Investment Results
Final Value:
$0.00
Total Invested:
$0.00
Total Profit:
$0.00
ROI:
0.00%
Annualized Return (CAGR):
0.00%
Investment Calculator: key facts
- What it does
- ROI & growth projections
- Category
- Financial Calculators
- Cost
- Free, with no account, sign-up, or install.
- Your data
- Runs entirely in your browser — the files and text you enter are never uploaded to a server.
- Last reviewed
- . Report an incorrect result.
What the Investment Calculator does
Investing is a long game, and seeing the trajectory makes it easier to stick with. The Investment Calculator combines a starting amount with regular monthly contributions and an expected annual return, then projects the final value — backed by a year-by-year table showing how the balance, contributions, and profit grow.
It suits anyone building wealth steadily: someone modeling a retirement account, a parent saving toward college, or an investor sanity-checking whether a contribution rate meets a goal. Beyond the headline number, it reports total invested, total profit, simple ROI, and an annualized return, so you understand not just where you end up but how efficiently you got there.
Using the Investment Calculator, step by step
- Enter your initial investment.
- Enter your monthly contribution.
- Enter the expected annual return as a percentage and the investment period in years.
- Read the final value, total invested, total profit, ROI, and annualized return.
- Expand the yearly projection to see the balance build year by year.
How the projection is built
The balance is modelled in two parts and added together. The opening amount compounds monthly for the whole term. The monthly contributions are valued as an ordinary annuity, which treats each one as arriving at the end of its month and compounding only across the months that follow it.
Compounding is monthly regardless of the annual return you enter, so an 8% expectation is applied as roughly 0.667% twelve times a year. The yearly table recomputes both components at each year boundary rather than interpolating between them.
The annualised figure deserves a caveat, because it is not the return you typed in. It is computed by comparing the final balance against the total amount contributed, and since contributions arrive gradually rather than all at the start, most of them have been invested for far less than the full term. That makes the annualised number substantially lower than the assumed return — it is closer to a return on total money committed than a rate of growth.
- The defaults — 10,000 opening, 500 a month, 8% for 10 years — reach 113,669.42.
- Of that, 70,000 is money contributed and 43,669.42 is growth. Growth passes contributions somewhere in the ninth year on these inputs.
- The annualised figure reported for that scenario is 4.97%, not 8%, for the reason described above — the average pound was invested for about half the term.
What makes this one worth using
- It pairs a lump sum with recurring monthly contributions and shows a full year-by-year projection, so compounding growth is visible rather than abstract.
- It reports both simple ROI and annualized return (CAGR), separating the headline gain from the time-adjusted rate.
- Total invested is shown next to total profit, making clear how much of the final value you contributed versus what the market added.
- Everything is computed locally and instantly, with no account or data sharing.
Treating the output as a scenario, not a forecast
A fixed expected return is a modelling device. Real markets deliver their long-run average through sequences of strong and weak years, and the order matters — particularly once you begin withdrawing, where early losses do lasting damage that the same losses later would not. Run a pessimistic return alongside your central one and read the pair as a range.
Three things are excluded and all of them reduce the outcome. Inflation, so a balance decades out is quoted in nominal money rather than purchasing power. Tax on dividends, interest, and gains. And charges — platform fees, fund expenses, and trading costs, where even one percent a year removes a surprisingly large share of a long-horizon balance. Past performance does not indicate future results, and nothing on this page is investment advice.
Frequently Asked Questions
How is this different from a compound interest calculator?
A compound interest tool typically grows a single balance. This calculator adds regular monthly contributions on top of that growth and produces a year-by-year projection plus ROI and annualized-return metrics, modeling an ongoing investing habit rather than a one-time deposit.
What return rate should I assume?
Returns are never guaranteed, but many long-term investors model broad stock-market averages in the range of roughly 6–8% annually before inflation. Use a rate you can justify for your strategy, and test a conservative figure alongside an optimistic one.
Does this account for inflation or taxes?
No. The projection shows nominal growth before inflation and taxes. To gauge real purchasing power, mentally discount the result by your inflation assumption, and remember that taxes on gains depend on the account type and jurisdiction.
How much should I contribute each month?
There is no universal figure — it depends on your goal, timeline, and income. The power of this calculator is showing how even modest, consistent contributions compound over years. Try a contribution you can sustain, then raise it to see how much sooner you reach your target.
