Compound Interest Calculator

Free compound interest calculator. See how your savings and investments grow over time with the power of compounding. Calculate future value, total interest earned, and yearly breakdown.

Initial Investment

Monthly Contribution

Annual Interest Rate: 7%

0%25%

Time Period: 20 years

1 yr50 yrs

Compounding Frequency

Future Value

$300,351

Total Contributed

$129,500

Interest Earned

$170,851

Breakdown

Contributions (43%)Interest (57%)

Year-by-Year Breakdown

Year	Balance	Contributed	Interest
1	$16,419	$15,500	$919
2	$23,839	$21,500	$2,339
3	$31,794	$27,500	$4,294
4	$40,325	$33,500	$6,825
5	$49,473	$39,500	$9,973
6	$59,282	$45,500	$13,782
7	$69,799	$51,500	$18,299
8	$81,078	$57,500	$23,578
9	$93,171	$63,500	$29,671
10	$106,139	$69,500	$36,639
11	$120,044	$75,500	$44,544
12	$134,955	$81,500	$53,455
13	$150,943	$87,500	$63,443
14	$168,087	$93,500	$74,587
15	$186,471	$99,500	$86,971
16	$206,183	$105,500	$100,683
17	$227,320	$111,500	$115,820
18	$249,986	$117,500	$132,486
19	$274,290	$123,500	$150,790
20	$300,351	$129,500	$170,851

How Compound Interest Works

Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. Unlike simple interest, which only earns on the original amount, compound interest accelerates your wealth growth exponentially over time.

The formula is: A = P(1 + r/n)^(nt), where P is the principal, r is the annual rate, n is the compounding frequency, and t is time in years. Adding regular monthly contributions dramatically increases the final value through dollar-cost averaging.

For example, investing $10,000 at 7% annual return with $500 monthly contributions for 20 years can grow to over $300,000 — with more than half of that coming from compound interest alone. Starting early is the single most powerful factor in building wealth.