Compound Interest Calculator
See how your starting investment and regular deposits could grow over time. Include fees and inflation to compare future dollars with today’s buying power.
Inputs used
How much could regular investing grow over time?
Scenario links include your inputs in the URL fragment. Anyone with the link can read them. Use hypothetical amounts when sharing.Adjust the inputs to compare possibilities.
What this means
Contributions and growth are differentThe ending balance combines money contributed with hypothetical growth. Compare the purchasing-power figure to see what inflation changes. Try changing the timeline before the assumed return.
Free educational illustration only. Results depend on your assumptions and may not fit your circumstances. This tool does not provide individualized advice; do not use it as your sole basis for a financial decision. Read the financial disclosures.
Illustrative assumptions only. Returns are constant in this model; real investments fluctuate. Fees are approximated as a reduction in annual return. Taxes are excluded. Lower and higher return examples are selected comparisons, not a probability range, guaranteed bounds, or worst-case loss estimate; actual outcomes can fall outside them.
How this calculator works
Annual return inputs are effective annual assumptions, converted to an equivalent periodic rate. Growth compounds each period. Contributions are added at the end of each selected period. Fees reduce the assumed effective annual return before inflation; purchasing power is divided by (1 + inflation) raised to years.
Model assumptions: Illustrative assumptions only. Returns are constant in this model; real investments fluctuate. Fees are approximated as a reduction in annual return. Taxes are excluded.
Model reviewed: October 10, 2026. Outputs are rounded for display; calculations use unrounded values. Defaults and return comparisons are illustrative, not recommended assumptions.
Worked example
Starting with $5,000 and adding $500 at each month-end for 25 years, a 7% effective annual return before a 0.1% fee illustrates an ending balance of $412,288.30. At 2.5% annual inflation, its purchasing power is $222,384.43 in today’s dollars.
Hypothetical example, calculated with this tool’s model; not a forecast or recommended assumption.
Load this example in the calculator ↗Common questions
Does this calculator include fees and inflation?
Yes. The fee input reduces the assumed annual return. The tool shows both the ending dollar balance and its purchasing power after your chosen inflation assumption.
What does changing contribution frequency mean?
The contribution amount applies each selected period. For example, $500 monthly means $6,000 per year, while $500 quarterly means $2,000 per year. Contributions are added at period-end; return inputs are effective annual rates.