See how a starting balance and ongoing contributions may grow. Choose a compounding frequency, contribution schedule, and optional annual increase to compare future value with estimated purchasing power today.
Flexible contribution timing • Year-by-year growth • Calculated in your browserYear-by-year projection
| Year | Contributions this year | Total contributed | Interest earned | Ending balance | Inflation-adjusted value |
|---|
The inflation-adjusted value expresses each year-end balance in estimated purchasing power at the start of the projection.
How to use this compound interest calculator
Enter your starting balance, regular contribution, annual nominal rate, and investment period. Choose the contribution interval and when each contribution is made. Select how often interest compounds. To model rising contributions or compare an inflation-adjusted value, select the optional settings and enter your estimates.
How compound growth works
Compound interest is calculated on the starting balance and on interest previously added to the account. Regular contributions add new money over time. Contributions made at the beginning of a period earn interest for that period; contributions made at the end begin earning interest in the next period.
View the calculation method and assumptions
For a nominal annual rate j compounded m times per year, this calculator converts the compounding convention to an equivalent rate for each contribution period f: r = (1 + j/m)m/f − 1. It then applies that rate once each contribution period. At 0%, the balance grows only through deposits. This conversion gives a consistent periodic projection when the contribution and compounding frequencies differ.
Contributions are assumed to occur at equally spaced intervals. When annual increases are enabled, the contribution amount increases by the selected percentage after each completed year. Inflation-adjusted value is ending balance divided by (1 + estimated annual inflation)years. No tax, fees, volatility, or withdrawals are modeled.
Example: regular monthly investing
Suppose you start with $1,000, contribute $100 at the end of every month, earn a constant nominal annual rate of 5% compounded monthly, and invest for 10 years. The calculator applies the monthly rate to the balance each month and adds the contribution at the end of that month. The result is a mathematical illustration; actual investment returns vary and are not guaranteed.
Nominal balance and purchasing power
The nominal balance is the projected account value in future dollars (or the selected display currency). Inflation reduces what that amount may buy. The inflation-adjusted value estimates its purchasing power in today’s money using the inflation rate you supply. It is a planning comparison rather than a forecast of future inflation.
Understanding the results
- Ending balance: starting amount, contributions, and modeled interest combined.
- Total contributed: starting balance plus all scheduled deposits, including annual increases if enabled.
- Interest earned: projected ending balance minus the total amount contributed.
- Inflation-adjusted value: estimated purchasing power expressed in today’s currency.
Questions and limitations
Does this guarantee an investment return?
No. A constant rate is a simplifying assumption. Real investments can rise or fall, and returns may not occur evenly or at all.
Is the currency selector a currency converter?
No. It changes the currency symbol and number formatting only. Convert your inputs yourself before comparing values in another currency.
Does this include tax or fees?
No. Account fees, fund expenses, taxes, and withdrawal rules can reduce the actual result and are not included.
Are my inputs saved?
The calculator processes inputs in your browser and does not send them to this tool’s calculation code. Website hosting, analytics, or other plugins may have separate privacy practices.
This tool is for educational estimates and is not financial, tax, or investment advice.