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Compound Interest Calculator

Watch a balance grow from what you start with and what you add each month. Choose how often interest compounds.

Use 0 if you are not adding money.

Enter 7 for 7%.

A whole number from 1 to 50.

Contribution timing

Money added at the start earns that month. Money added at the end waits.

Ending balance

$54,713.58

After 10 years, compounding monthly.

  • Contributions and starting amount
  • Interest earned
Starting amount
$10,000.00
Total contributions
$24,000.00
Interest earned
$20,713.58

The guide explains how compound interest grows a balance over time.

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Year-by-year growth

Year-by-year compound growth, rounded to the cent for display
YearContributionsInterestEnd balance
Year 1$2,400.00$801.42$13,201.42
Year 2$2,400.00$1,032.85$16,634.27
Year 3$2,400.00$1,281.01$20,315.28
Year 4$2,400.00$1,547.11$24,262.39
Year 5$2,400.00$1,832.45$28,494.83
Year 6$2,400.00$2,138.41$33,033.24
Year 7$2,400.00$2,466.49$37,899.74
Year 8$2,400.00$2,818.29$43,118.03
Year 9$2,400.00$3,195.52$48,713.55
Year 10$2,400.00$3,600.02$54,713.58

How it's calculated

The annual rate is split across the compounding periods you choose, then applied as one month of growth. Daily compounding uses 365 periods, monthly uses 12, quarterly uses 4, and yearly uses 1. A contribution at the start of the month earns that month. A contribution at the end waits until the next month. The starting amount earns interest from the first month.

Monthly rate = (1 + annual rate ÷ periods)periods ÷ 12 − 1
Interest this month = balance × monthly rate

Reviewed by WH2L Digital. Last reviewed October 31, 2026.

Questions

What does compounding frequency change?

The same annual rate grows a little faster when it is applied more often. Daily compounding finishes higher than monthly, monthly higher than quarterly, and quarterly higher than yearly.

What is the difference between adding money at the start or the end of the month?

A contribution at the start of the month earns that month's interest. A contribution at the end waits until the next month. The starting amount earns interest either way.

What is counted as interest earned?

Interest earned is the ending balance minus the starting amount minus every monthly contribution. Contributions are not counted as interest.

Emergency FundAvailableTarget fund from essential monthly costs, the gap, and the month it would be full.CDAvailableEnding balance, interest, maturity date, and the APR or APY that matches the rate you enter.Debt PayoffAvailableDebt-free date, total interest, payoff order, and a month-by-month plan.

Educational estimates only, not financial advice.