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Investment Growth Calculator

Updated January 2026

An investment calculator gives you a realistic projection of how your money can grow over time through the power of compounding returns. Whether you have a lump sum to invest or plan to contribute regularly, this tool shows your potential future value.

How to Use This Calculator

Start by entering your current investment balance, then the amount you'll contribute each month. Enter your expected annual return rate, the number of years you plan to invest, and an estimated inflation rate. The calculator shows your projected future value in nominal and inflation-adjusted terms, so you can see the true purchasing power of your savings.

How It's Calculated

The future value combines lump sum growth with the future value of an annuity for recurring contributions:

FV = P × (1 + r/n)^(n×t) + PMT × [ ((1 + r/n)^(n×t) − 1) / (r/n) ]

With inflation adjustment: Real FV = FV / (1 + inflation_rate)^t, giving you a more honest picture of what your future savings will be worth in today's dollars.

Frequently Asked Questions

This depends on your initial investment, ongoing contributions, and average annual return. Historically, the S&P 500 has averaged about 10% annual returns before inflation (about 7% after inflation). A $10,000 lump sum with $500 monthly contributions at 8% would grow to approximately $97,000 in 10 years, $306,000 in 20 years, and $765,000 in 30 years. Use this calculator to model your specific numbers.
For long-term stock market investments, a reasonable assumption is 6–10% annual returns before inflation. Conservative investors often use 6–7%, moderate investors use 7–8%, and aggressive investors use 9–10%. For bonds, assume 3–5%. It's wise to run multiple scenarios with different return rates and to remember that past performance doesn't guarantee future results. Our calculator also shows inflation-adjusted returns for a more realistic picture.
Yes, this calculator offers an optional inflation adjustment toggle. When enabled, it shows the "real" (inflation-adjusted) future value alongside the nominal future value. With historical inflation averaging about 3% per year, $1,000,000 in 30 years is worth only about $412,000 in today's purchasing power. Always consider inflation when setting long-term financial goals to ensure your savings will actually buy what you expect.

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