Investment Calculator
Project investment growth with compound interest. Includes inflation adjustment to see real vs nominal returns.
Future Value: —
| Year | Contrib. | Interest | Balance | Real Value |
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Investment Calculator
An investment calculator shows how your money can grow over time through the power of compound interest. Enter your initial investment, monthly contribution, expected annual return, and investment period to see the projected future value of your portfolio.
Numbrary goes further by including an inflation rate — so you see both the nominal value and the real (inflation-adjusted) purchasing power of your money in today's dollars.
You can choose monthly, quarterly, or annual compounding, and the year-by-year table breaks down your contributions, interest earned, and balance for up to 30 years — perfect for retirement planning.
Frequently Asked Questions
What is compound interest?
Compound interest is interest earned on both your original money and the interest that money has already earned. Over long periods it grows exponentially — this is why starting early matters so much.
What return rate should I use?
A common planning assumption is 7–10% for a diversified stock portfolio before inflation, or 4–6% after inflation. Historical long-run averages for the S&P 500 are around 10% nominal.
Why does inflation matter?
Inflation reduces what your future dollars can buy. Adjusting for inflation (real returns) gives you a more honest picture of your future purchasing power.
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