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Compound Interest
✦ ProSee how your investments grow over time. Enter your starting amount, monthly contributions, interest rate, and time horizon.
$
$
%
years
Final Balance
$300,851
Total Contributions
$130,000
Total Interest Earned
$170,851
Growth Over Time
$16,919
Year 1
$24,339
Year 2
$32,294
Year 3
$40,825
Year 4
$49,973
Year 5
$59,782
Year 6
$70,299
Year 7
$81,578
Year 8
$93,671
Year 9
$106,639
Year 10
$120,544
Year 11
$135,455
Year 12
$151,443
Year 13
$168,587
Year 14
$186,971
Year 15
$206,683
Year 16
$227,820
Year 17
$250,486
Year 18
$274,790
Year 19
$300,851
Year 20
Contributions
Interest
Frequently Asked Questions
What is compound interest?
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest (calculated only on the principal), compound interest makes your money grow faster over time — often called "interest on interest."
What is the compound interest formula?
The formula is A = P(1 + r/n)^(nt), where A is the final amount, P is the principal, r is the annual interest rate (decimal), n is the number of times interest compounds per year, and t is the number of years.
How often does interest compound?
Interest can compound daily, monthly, quarterly, or annually. The more frequently it compounds, the faster your money grows. Most savings accounts compound daily or monthly, while many investment returns are expressed as annual rates.
How does the Rule of 72 work?
The Rule of 72 is a quick way to estimate how long it takes to double your money. Divide 72 by your annual interest rate. For example, at 8% interest: 72 ÷ 8 = 9 years to double your investment.
What is the difference between compound interest and simple interest?
Simple interest is calculated only on the original principal (e.g., $1,000 at 5% = $50/year forever). Compound interest is calculated on the principal plus accumulated interest, so you earn interest on your interest, leading to exponential growth over time.
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