Project the future value of your investments over time, adjusted for inflation.
Long-term investing is fundamentally a question of probability and patience rather than precision, but having a clear quantitative model of how a portfolio might grow under reasonable assumptions is essential for setting realistic financial goals. The CalcEqual Investment Calculator projects the future value of an investment portfolio based on a starting amount, ongoing monthly contributions, an assumed average annual return, and the time horizon — while also showing the inflation-adjusted value so you understand what that future sum will actually be worth in today's purchasing power.
Financial advisors and individual investors alike use tools like this during goal-setting conversations: how much do I need to contribute monthly to reach a $1 million retirement target by age 65? What's the realistic gap between an aggressive 9% average return assumption versus a conservative 5% assumption over 30 years? This calculator makes those scenario comparisons immediate and visual.
It's important to treat the "expected annual return" input as a long-term historical average, not a guaranteed or smooth year-to-year figure — real markets are volatile, and any single year's return can deviate enormously from the long-term average used in this projection.
Diversification across asset classes — stocks, bonds, real estate, and cash equivalents — is a separate but related concept from the pure compounding math this calculator models. While this tool assumes a single average annual return for simplicity, real portfolios typically blend multiple asset types with different risk and return profiles, and the assumed "expected annual return" entered here should reflect a reasonable blended estimate for your actual asset allocation, not the historical return of any single asset class in isolation.
This calculator combines lump-sum compound growth with the future value of a recurring contribution series (an ordinary annuity), then deflates the nominal total by an assumed inflation rate:
The historical average annual return of the S&P 500 index, a commonly used benchmark for U.S. equity market performance, has been approximately 10% nominal (around 7% after adjusting for historical average inflation) over long multi-decade periods since its modern form was established in 1957 — though any individual decade can vary substantially above or below this long-run average.
The U.S. Securities and Exchange Commission requires that any investment return projections used in marketing materials include disclosure that past performance does not guarantee future results, and FINRA-regulated broker-dealers must ensure projections presented to clients are based on reasonable assumptions, not cherry-picked historical periods designed to produce an unrealistically rosy outcome.
Tax-advantaged account types also meaningfully change effective investment outcomes. Contributions to a Roth IRA grow tax-free and can be withdrawn tax-free in retirement, while a traditional 401(k) grows tax-deferred but is taxed upon withdrawal — the "best" choice depends on your current versus expected future tax bracket, a decision separate from the pure growth math this calculator models.
Robo-advisors and target-date funds have also made disciplined, automated investing more accessible to non-experts in recent years, automatically adjusting asset allocation over time according to a preset glide path — a useful option for investors who want exposure to long-term compounding without actively managing individual security selection themselves.
Future value of $500/month invested for 20 years at different return assumptions (no initial lump sum):