The formula
We apply A = P(1 + r/n)^{nt} where P is the starting amount, r is the annual rate, n is compounding periods per year and t is years. Contributions are added by treating each deposit as its own compounding series.
Calculator
Compound Interest Calculator
Estimate investment growth with optional periodic contributions.
Result
Future value$16470.09
Interest earned$6470.09
Total contributions$10000.00
Growth Contributions
Solid line shows projected balance. Dashed line shows total contributions over time.
Guide
How Compound Interest Works
Compound interest grows your savings by applying interest to both the original principal and the interest that has already accrued. Our calculator lets you add recurring contributions so you can see when your deposits get overtaken by growth.
- Supports any compounding frequency and contribution schedule.
- Plots total balance vs. total contributions for clarity.
- Shows future value, total interest earned and total contributions.
Contribution impact
Setting a recurring contribution shows how much of the final balance came from your deposits versus growth. This helps you decide whether to increase deposits, chase higher rates or extend the time horizon.
Reading the chart
The solid line is projected balance while the dashed line is total contributions. When the solid line moves above the dashed line, compound interest has overtaken the money you put in—a key milestone for long-term investors.
Source: Compound interest – Wikipedia