AN EDUCATION IN TIME
See what time can do to a simple plan.
Compound interest is the quiet result of earning returns on prior returns, then allowing that process time. This illustration keeps every assumption visible.
- 04 clear inputs
- 01 visible formula
- 00 return promises
WEALTHPAST TOOLS
Compound Interest Calculator
Use your own assumptions to explore how time, contributions, and compounding can affect an estimated future balance.
For educational purposes only. This calculator provides estimates, does not account for taxes, fees, inflation, or market volatility, and is not financial advice.
THE SHAPE OF TIME
See the curve change as time accumulates.
Each marker uses the same assumptions above. The curve rises when returns begin earning returns of their own.
AT YEAR 20
$158,129$90,129 from growth
THE SHORT GUIDE
Compounding becomes clearer when the assumptions stay visible.
Start with a rate you can explain.
The rate is an assumption, not a promise. It is most useful when its limits are understood.
Make the deposit timing explicit.
This tool applies the same contribution at the end of each month, so the model does not hide a timing choice.
Separate illustration from reality.
Real returns, fees, taxes, inflation, and contributions can change. A projection is a way to think, not a guarantee.
SOURCES & METHOD
The method keeps the monthly order explicit.
The starting balance grows at the stated annual rate and frequency. Each month-end contribution grows for the remaining period using the equivalent monthly rate.
plus monthly contribution × [((1 + equivalent monthly rate)^months − 1) ÷ equivalent monthly rate]
The calculator assumes a constant stated rate and a contribution at each month-end. It does not account for fees, taxes, inflation, varying returns, changes in contributions, or investment losses. It is educational information—not personal investment, financial, legal, or tax advice.