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Investment Calculator

Project the future value of your investments. Add a monthly contribution, set your expected return, and see exactly how much comes from your own money versus compound growth - year by year.

  • 100% free
  • No signup
  • Runs in your browser
Compounding
Final balance
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Total contributed
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Total growth
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Contributions Growth
Year Contributions Growth Balance
Guide

How investment growth is projected

This calculator projects the future value of an investment by combining three things: your starting amount, your regular contributions, and compound growth at an assumed annual return. Each contribution is added to the balance and then grows for the rest of the time horizon, so money you invest early does the most work. The result separates how much of the final total came from your own deposits versus how much came from growth, which is often the most eye-opening part.

What return rate should you use?

There is no single correct number, so use a realistic, conservative estimate rather than a hopeful one. Historically, broad stock-market indexes have returned roughly 7% to 10% per year on average over long periods, before inflation, but with large swings along the way. Bonds and cash return less. It is wise to run the projection at a few different rates to see a range of outcomes rather than betting on one figure.

Does this account for inflation?

The projection shows nominal (face-value) future dollars. Inflation reduces what those dollars will buy, so a balance that looks large in 30 years will have less purchasing power than the same number today. A common adjustment is to subtract your expected inflation rate (often assumed around 2% to 3%) from your return to estimate growth in today's money.

Taxes and real-world frictions

Real returns are also affected by taxes on gains and dividends, and by fund fees. Tax-advantaged accounts (such as retirement accounts) can shelter growth, while taxable accounts may owe tax along the way. This tool models the math of compounding, not your specific tax situation, so treat the output as an illustration of the mechanics rather than a precise forecast.

Projections are illustrative and assume a constant return. This is not investment advice; past performance does not guarantee future results.

Last updated: July 2026

Frequently Asked Questions

How is investment growth calculated?
This calculator applies a future-value formula: your initial amount and each monthly contribution earn compound returns over time. Interest is applied at your chosen compounding frequency, and the balance grows on both your contributions and previously earned growth.
What return rate should I use?
A common long-term assumption for a diversified stock-market portfolio is 6–8% annually before inflation. Bonds and cash typically return less. Use a conservative estimate - past performance does not guarantee future results.
Does this account for inflation?
No. The projection shows nominal (not inflation-adjusted) dollars. To estimate real purchasing power, subtract your expected inflation rate (often ~2–3%) from your return rate before entering it.
What is the difference between monthly and annual compounding?
Monthly compounding applies interest twelve times a year, so growth earns growth sooner, producing a slightly higher final balance than annual compounding at the same nominal rate. The difference grows over long time horizons.
Should I include taxes?
This tool does not deduct taxes. Returns in tax-advantaged accounts (like a 401(k) or IRA) grow untaxed until withdrawal, while taxable accounts may owe tax on dividends and gains. For an after-tax estimate, lower your return rate accordingly.
Can I model irregular contributions?
This calculator assumes a constant monthly contribution. For one-off lump sums or changing contributions, run separate scenarios and add the results, or adjust the monthly amount to an average that approximates your plan.