Calculator Suite

Investment ROI Calculator

Calculate compound interest returns, future value, and investment growth projections

Investment Details
Enter your investment parameters to calculate future value and ROI

Your starting investment amount

Amount you'll invest each month

Expected yearly return on your investment

How long you'll invest for

How often returns are compounded

$6,000.00

Monthly contribution × 12 months = Total yearly investment

Expected annual inflation rate for real value calculations

When you'll start investing

Initial Investment Presets

$1,000$5,000$10,000$25,000$50,000$100,000

Monthly Contribution Presets

$0$100$250$500$1,000$2,500$5,000

Expected Return Rates

Conservative (4%)Moderate (7%)Aggressive (10%)S&P 500 Avg (11%)High Growth (15%)
How this calculator works
Method, formula, examples, assumptions, and review notes for this calculator.

How this calculator works

  • The calculator compounds the initial investment at the selected frequency.
  • Recurring contributions are added on the schedule used by the projection model and then compound over the remaining horizon.
  • If inflation is entered, a separate real-value estimate discounts the future value back to today's purchasing power.

Formula

Future value with compound growth

FV=P(1+rm)mt+C(1+rm)mt−1rmFV = P(1 + \frac{r}{m})^{mt} + C \frac{(1 + \frac{r}{m})^{mt} - 1}{\frac{r}{m}}

Plain text formula: Future value = compounded starting principal plus the future value of recurring contributions.

FV = projected future value
P = initial investment
r = annual return rate as a decimal
m = compounding periods per year
t = number of years
C = contribution per compounding period

Worked examples

Long-term monthly investing

Inputs

  • Initial investment: $10,000
  • Monthly contribution: $500
  • Annual return: 7%
  • Time horizon: 20 years

Calculation

  • Total contributions over 20 years are $130,000.
  • Compound growth adds return on both the initial investment and accumulated contributions.
  • The future value estimate is about $293,918 before taxes and fees in the default monthly model.

Most growth may arrive late in the timeline because compounding has more accumulated balance to act on.

Curated video guide
Selected YouTube lessons that add context after the calculator, formulas, examples, assumptions, and limitations.

Compound interest introduction

Source: Khan Academy on YouTube

Why this video: Selected because it teaches compound growth from a neutral educational perspective rather than promising investment results.

What it adds: It supplements the future value model by showing why interest-on-interest can dominate long time horizons.

Use with this calculator: Enter a simple scenario in the calculator, then use the video to understand why changing time or rate changes future value.

Limits: The lesson is mathematical education only; it does not model taxes, fees, volatility, inflation shocks, or investment suitability.

How to interpret your result

  • Treat the result as a scenario estimate, not a prediction.
  • Compare nominal value with real value when inflation is included, because purchasing power can be much lower than the future dollar amount.

Assumptions

  • The annual return rate is constant for the full period.
  • Contributions are made consistently at the entered amount.
  • Inflation, when included, is constant and compounded annually in the projection.

Limitations

  • The model does not include taxes, investment fees, trading costs, or sequence-of-return risk.
  • Real markets are volatile and do not produce the same return every year.
  • The calculator does not recommend a portfolio, asset allocation, or security.

Common mistakes

  • Using a historical average as if it were a guaranteed future return.
  • Ignoring fees and taxes when comparing investments.
  • Comparing nominal future dollars without considering inflation.

Sources

SEC Investor.gov: investor education and calculatorsSEC Investor.gov resources for investors

Disclaimer

Last updated and reviewed by

Updated 2026-06-06Calculator Suite editorial review