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Compound interest with monthly contributions

See what the habit of investing every month earns: enter the contribution, the rate and the term and compare the total invested with the interest.

Compound interest calculator

In 10 years you will have

$115,019.34

Invested
$60,000.00
Interest
$55,019.34
InvestedInterest
030K60K90K120KToday5 years10 years

In 10 years you will have $115,019.34

$60,000.00 invested$55,019.34 in interest

Hover or tap the bars to see each moment.

Year-by-year growth
YearInvestedInterestTotal
1$6,000.00$341.25$6,341.25
2$12,000.00$1,486.73$13,486.73
3$18,000.00$3,538.44$21,538.44
4$24,000.00$6,611.30$30,611.30
5$30,000.00$10,834.83$40,834.83
6$36,000.00$16,354.97$52,354.97
7$42,000.00$23,336.14$65,336.14
8$48,000.00$31,963.65$79,963.65
9$54,000.00$42,446.29$96,446.29
10$60,000.00$55,019.34$115,019.34

How monthly contributions change the result

Monthly contributions grow the balance in two ways: the new money that comes in every month and the interest that money starts to earn. With $10,000.00 at 1% per month for 10 years and no contributions, the total reaches $33,003.87. Adding $500.00 per month, the total rises to $148,023.21, of which $70,000.00 invested and $78,023.21 interest.

The earlier contributions start, the more time they have to earn interest on interest. That is why the term usually matters more than the size of each installment.

Compound interest formula with contributions

With the contribution P made at the end of each month, the monthly rate i and n months, the final amount is the future value of the initial capital C plus the future value of the installments:

M = C × (1 + i)^n + P × [((1 + i)^n − 1) ÷ i]

Contribution at the start or the end of the month

This calculator assumes the contribution at the end of each month: the balance earns the month’s rate and then the installment is added. If you invest at the start of the month, the real result is slightly higher than the simulated one.