Grow · Compound interest
Compound interest calculator
See how an opening balance, regular contributions, and time can shape a future balance.
Scenario inputs
Change the assumptions.
- Starting balance
- Monthly contribution
- Annual rate (%)
- Time horizon (years)
Open the interactive calculator to enter values and share a link containing the scenario.
How it works
Time is the quiet variable.
This estimate compounds monthly and treats each monthly contribution as arriving at the end of the month. It is a planning illustration, not a projection of any specific investment.
The rate is an assumption you can change. Real returns are uneven, and this calculation does not model taxes, fees, or market volatility.
Common questions
Before you use the number.
What does compound interest mean?
Compound interest is growth earned on both the original balance and earlier growth. Contributions and the time horizon can materially change the result.
Are monthly contributions included?
Yes. The calculator adds the monthly contribution at the end of each month and compounds the balance monthly.
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