WorldCalcs

Investment Calculator

Estimate how much your portfolio could grow with regular contributions and compound returns.

Reviewed by the WorldCalcs team · Methodology · Last reviewed: July 2026

End balance

300 850.72

Total contributions

130 000.00

Total growth

170 850.72

This is a general estimate, not financial advice. Actual returns vary and are not guaranteed. See our Disclaimer.

What is an investment calculator?

An investment calculator estimates how much an investment could be worth in the future when you start with a lump sum, add money regularly, and let compound returns build over time. It shows your projected end balance, how much of that is your own contributions, and how much is investment growth. It is useful for planning a brokerage account, an index-fund portfolio, or any long-term savings goal. Returns are an assumption you choose, not a guarantee — real markets go up and down.

How investment growth is calculated

The projection combines two parts: the growth of your starting amount, and the growth of your regular contributions. The starting amount grows as P × (1 + i)^N, where i is the monthly return (annual return ÷ 12) and N is the number of months (years × 12). Each monthly contribution grows too, and their combined value is PMT × ((1 + i)^N − 1) ÷ i. Adding the two gives the future value. Because returns compound — you earn returns on previous returns — the growth accelerates the longer you stay invested. Total contributions are simply your starting amount plus every deposit; the rest of the balance is growth.

Example

Suppose you start with 10 000, add 500 every month, and assume a 7% average annual return for 20 years. The portfolio grows to 300 850.72. You contributed 130 000.00 over those years, so 170 850.72 of the final balance is compound growth. The same plan at a 0% return would leave you with only the 130 000.00 you deposited — the difference shows the power of compounding over time.

Related: see our Savings Calculator, Compound Interest Calculator and Retirement Calculator.

All calculations happen in your browser. Nothing is sent, stored, or tracked.

Results are estimates and may contain errors — for general information only, not professional advice. Always verify before relying on them. Disclaimer

How to use

Enter your starting amount, monthly contribution, expected annual return and time horizon. The projection updates instantly.

Open the year-by-year table to see how contributions and growth build the balance over time.

Frequently asked questions

How much will my investment grow?+

It depends on your starting amount, how much you add, your average return, and how long you stay invested. Enter those four numbers and the calculator estimates the future balance.

What return rate should I use?+

Use a realistic long-term average for your investment type. Many people model a broad stock-market portfolio somewhere around 6–8% before inflation, but this is an assumption, not a promise.

How is this different from a savings calculator?+

The math is the same compound-growth formula. An investment calculator frames the return as an expected market return, while a savings calculator usually models a fixed bank interest rate.

Does the calculator account for inflation?+

No. It shows nominal growth. To estimate purchasing power, subtract your expected inflation rate from the return you enter.

What is compound growth?+

Compounding means your returns earn their own returns. Over long periods this snowball effect makes up a large share of the final balance. See our compound interest calculator for the underlying math.

Are taxes and fees included?+

No. Results are before taxes and investment fees, which vary by account and country. Lower your return assumption slightly to approximate their effect.

How often are contributions added?+

This calculator assumes an equal contribution every month, with returns compounded monthly.

Is a guaranteed return realistic?+

No. Real investments fluctuate and can lose value. Treat the result as a planning estimate based on the average return you chose, not a guaranteed outcome.

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