See how compounding can change your money over time.
Start with a principal, annual rate and time horizon. Choose how often the rate compounds, then optionally add regular contributions and an inflation assumption.
Compounding is a mechanism, not a promise.
Learn why time, rate and contribution timing can change a projection—and why a smooth calculator curve is not the same as a market forecast.
Build the assumptions
Starting amount and rate
Use a stated annual rate as an assumption. For market investments, this is a modeled growth rate—not guaranteed interest.
Optional regular contributions
Add evenly spaced contributions if you want to see principal growth and ongoing saving together.
Advanced assumptions
Where the ending value comes from
Compare cumulative money contributed with the modeled compound balance over time.
Annual growth table
See cumulative contributions, ending balance and modeled growth at each year-end.
| Year | Total contributed | Ending balance | Growth | Today's money |
|---|
The web table shows up to 31 rows for readability. The CSV and report include the full annual series.
Compounding frequency changes the effective annual rate.
The starting principal uses the nominal annual rate and selected compounding frequency. Optional contributions are modeled at an equivalent periodic rate derived from the effective annual rate so contribution cadence can remain independent of compounding cadence.
FV = P × (1 + j/n)^(n×t)EAR = (1 + j/n)^n − 1Use the result as a scenario, not a forecast.
A bank deposit can have a stated interest convention. Market investments do not earn a smooth guaranteed rate, so an entered investment return should be interpreted as an assumption used to understand compounding mechanics.
- Country and currency control terminology and formatting; they do not perform FX conversion.
- Regular contributions are assumed to be evenly spaced.
- Simple interest is shown only as an educational mathematical comparison.
- Inflation-adjusted output is explicitly labeled in today's purchasing-power terms.