What does the Investment Calculator compute?

It calculates the future value of an investment given a starting principal, regular monthly or annual contributions, an expected annual return rate, and a time horizon in years. The result shows your projected portfolio value alongside a year-by-year breakdown.

What is a realistic annual return rate to use?

Future returns are uncertain. Compare positive, zero, and negative return scenarios instead of treating one rate as a prediction. This calculator assumes a constant rate and does not model volatility.

Can I model lump-sum investments with no recurring contributions?

Yes. Simply set the Additional Contribution field to 0 and enter your full investment amount as the Starting Principal. The calculator will project growth based on compound returns alone.

Does this account for inflation or taxes?

No. Results are pre-tax nominal values. A real annual rate is (1 + nominal rate) / (1 + inflation rate) - 1; for example, 8% and 3% give about 4.85%. When using a real rate, contribution amounts must also be expressed consistently in real terms.

Is this tool free and private?

Yes. The calculator is completely free to use. All calculations happen locally in your browser — no data is ever sent to a server.

Investment Calculator

Calculate the future value of your investments. Adjust for starting principal, recurring deposits, compound return rates, and duration.

Investment Growth Widget

The annual return is an effective annual rate. Monthly or yearly contributions are added at the end of each period. Zero and negative returns above −100% are supported.

Starting Principal

Additional Contribution

Contribution Frequency

Expected Annual Return (%)

Duration (Years)

Calculation Result

Enter inputs above and click Calculate to view results.

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Worked example

Example: start with 0, add 100 at each month-end, and use a 12% effective annual return for one year. The projected balance is 1,264.65 on contributions of 1,200.

Investment Growth Widget

Calculation Result

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Worked example

Frequently Asked Questions