Monthly Compound Interest Calculator

With monthly compounding, one twelfth of the annual rate is added to the balance every month, and next month's interest is paid on that too. Enter a starting balance, the annual rate, an optional monthly deposit and the number of years to see the balance, the interest earned and the effective annual yield.

Final balance
$50,969.84
Total interest earned
$16,969.84
Total deposited
$34,000.00
Monthly rate (APR ÷ 12)
0.5%
Effective annual yield (APY)
6.168%
Interest in the first month
$50.00
YearBalanceDepositedInterest
1$13,083.89$12,400.00$683.89
2$16,357.99$14,800.00$1,557.99
3$19,834.03$17,200.00$2,634.03
4$23,524.46$19,600.00$3,924.46
5$27,442.51$22,000.00$5,442.51
6$31,602.21$24,400.00$7,202.21
7$36,018.48$26,800.00$9,218.48
8$40,707.14$29,200.00$11,507.14
9$45,684.97$31,600.00$14,084.97
10$50,969.84$34,000.00$16,969.84

Interest is added once a month at APR ÷ 12 and deposits are made at the end of each month. Results are estimates, not financial advice.

Example: $10,000 plus $200 a month at 6%, compounded monthly

YearBalanceTotal depositedInterest earned
1$13,083.89$12,400.00$683.89
2$16,357.99$14,800.00$1,557.99
3$19,834.03$17,200.00$2,634.03
5$27,442.51$22,000.00$5,442.51
10$50,969.84$34,000.00$16,969.84

Monthly compounding table: $10,000, no deposits

Annual rateMonthly rateAPYAfter 5 yearsAfter 10 years
2%0.1667%2.018%$11,050.79$12,211.99
4%0.3333%4.074%$12,209.97$14,908.33
5%0.4167%5.116%$12,833.59$16,470.09
6%0.5%6.168%$13,488.50$18,193.97
8%0.6667%8.3%$14,898.46$22,196.40
10%0.8333%10.471%$16,453.09$27,070.41

The formula

A = P × (1 + r/12)12t + D × ((1 + r/12)12t − 1) / (r/12), where P is the starting balance, r the annual rate, t the years and D the monthly deposit. For interest added every day instead, use the daily compound interest calculator; to compare rates quoted by APY, see the APR to APY calculator.

Frequently asked questions

How do you calculate compound interest monthly?

Use A = P × (1 + r/12)^(12 × t), where P is the starting balance, r the annual rate as a decimal and t the number of years. $10,000 at 6% for 10 years grows to about $18,194.

What is the formula with monthly deposits?

Add the future value of the deposits: D × ((1 + r/12)^(12t) − 1) / (r/12), where D is the deposit made at the end of each month. The calculator adds this to P × (1 + r/12)^(12t).

What is the APY of a rate compounded monthly?

APY = (1 + r/12)^12 − 1. A 6% rate compounded monthly gives an APY of about 6.168%, slightly more than 6% because each month’s interest earns interest for the rest of the year.

Is monthly or daily compounding better?

Daily is marginally better: at 6%, daily compounding gives an APY of about 6.183% against 6.168% for monthly. On $10,000 that is about $1.50 a year.

How much is 5% interest per month on $10,000?

A 5% annual rate compounded monthly is 5% ÷ 12 ≈ 0.4167% a month, so $10,000 earns about $41.67 in the first month and a little more each month after.

Sources

Last reviewed by the Quick Compound Interest Calculator team. Results are estimates for education, not financial advice.