Investment calculators
Free tools for exploring the math—not predicting the market.
Research and educational purposes only. Not investment advice. Results are hypothetical, not guarantees or recommendations.
Explore investment growth
Change the example amounts and enter your own return assumption. The starting 0% rate is a neutral illustration, not a recommended return.
How this calculation works
The monthly rate is (1 + annual return ÷ 100) raised to 1/12, minus 1. Each month, the previous balance grows by that rate, then the monthly contribution is added. Contributions stay constant in nominal dollars. Total contributed includes the starting amount.
Today’s dollars = ending value ÷ (1 + inflation ÷ 100) raised to the number of years. Calculations use unrounded values internally; displayed amounts are rounded to cents. Taxes, fees, withdrawals, changing returns, and separate dividend payments are not modeled. Any reinvested income must already be included in your assumed return.
Calculate a return from your own prices
Enter both prices yourself. This tool does not look up stocks, dates, or current prices, and does not verify your figures.
Price assumptions and limitations
Ending value = amount invested × ending price ÷ purchase price. Fractional shares are allowed; all of the entered amount is invested. Gain or loss equals ending value minus the invested amount. No later contributions or withdrawals are included.
Use the same currency and a consistent share basis for both prices. Splits and other corporate actions are not adjusted automatically. Unadjusted prices across a stock split can give a misleading result. Dividends, fees, taxes, and inflation are excluded. This is a simple price-change calculation, not a verified historical total return.