Compound Interest Calculator

Estimate how an initial investment and recurring deposits can grow with compound returns over time.

Assumptions

Results

Final balance
$196,665
Total contributions
$82,000
Interest earned
$114,665
Rule of 72 doubling time
10.3 years
YearCalendar yearContributionBalance
12026$13,600$14,441
52030$28,000$35,654
102035$46,000$72,022
152040$64,000$123,578
202045$82,000$196,665

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How compound interest works

Compound interest adds each period's interest back into the balance, so future interest is earned on both your original principal and previous interest. Longer time horizons make the effect more visible, especially when monthly contributions continue through the investment period.

What to compare

Adjust the annual return, investment period, and monthly contribution together. Small changes can produce large differences over 10, 20, or 30 years, so it is useful to test conservative and optimistic assumptions before setting a target.