Compound Interest Calculator

See how your money grows with compound interest. Add monthly contributions and compare compounding frequencies.

Balance after 20 years

$144,573

Total contributed
$58,000
Interest earned
$86,573
Year-by-year growth
YearContributedInterestBalance
1$12,400$801$13,201
2$14,800$1,834$16,634
3$17,200$3,115$20,315
4$19,600$4,662$24,262
5$22,000$6,495$28,495
6$24,400$8,633$33,033
7$26,800$11,100$37,900
8$29,200$13,918$43,118
9$31,600$17,114$48,714
10$34,000$20,714$54,714
11$36,400$24,747$61,147
12$38,800$29,246$68,046
13$41,200$34,244$75,444
14$43,600$39,776$83,376
15$46,000$45,882$91,882
16$48,400$52,603$101,003
17$50,800$59,983$110,783
18$53,200$68,070$121,270
19$55,600$76,915$132,515
20$58,000$86,573$144,573

How to use Compound Interest Calculator

  1. Enter your starting amount and monthly contribution.
  2. Enter the annual interest rate, years and compounding frequency.
  3. See your final balance, total interest and yearly growth.

How compound interest works

Compound interest earns interest on your interest. Each period, interest is added to the balance, so the next period earns interest on a larger amount. Over long periods this snowball effect becomes very powerful.

The rule of 72

Divide 72 by your annual interest rate to estimate how many years it takes to double your money. At 8%, money doubles in about 9 years.

Why starting early matters

Investing 200 a month at 7% for 30 years grows to about 244,000, of which only 72,000 is your own money. Waiting 10 years and investing for 20 years instead gives about 104,000. Time is the biggest driver of compound growth.

Frequently asked questions

Does compounding frequency matter?

Yes, slightly. Monthly compounding earns a bit more than yearly at the same rate, but the rate and time invested matter far more.

Is this financial advice?

No. Results are estimates for planning only. Real returns vary and investments can lose value.

Last updated: · Free to use, no sign-up.

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