Compound Interest Calculator

$1000/month at 7% for 30 years grows to $1,227,087

At 7% compound interest with $1,000/month contributions, your monthly investments grow to $1,227,087 over 30 years โ€” earning $867,087 in compound interest.

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Final balance
$1,227,087
After 30 years
Interest earned
$867,087
241% return
Total deposited
$360,000
Your contributions

What $1000/month at 7% for 30 years really means

By investing $1,000 every month for 30 years at 7%, you contribute a total of $360,000. Compound interest then adds another $867,087 โ€” money you earned without working for it. That's a 241% return on your actual contributions.

At 7% interest, money doubles every approximately 10.3 years (the Rule of 72). In the first year you earn $35 in interest. In year 30, you earn significantly more โ€” because you're earning interest on all the accumulated gains from prior years.

This is why time is the most powerful variable in compound interest. Starting 30 years earlier with the same contribution would produce dramatically more than doubling the contribution amount. Use the full compound interest calculator to model your exact scenario, or compare with a high-interest savings account.

Growth over 30 years
BalanceDeposited

Year-by-year breakdown

YearDepositedInterestBalance
Year 1$12,000$465$12,465
Year 2$24,000$1,831$25,831
Year 3$36,000$4,163$40,163
Year 4$48,000$7,531$55,531
Year 5$60,000$12,011$72,011
Year 6$72,000$17,681$89,681
Year 7$84,000$24,629$108,629
Year 8$96,000$32,947$128,947
Year 9$108,000$42,733$150,733
Year 10$120,000$54,094$174,094
Year 11$132,000$67,145$199,145
Year 12$144,000$82,006$226,006
Year 13$156,000$98,809$254,809
Year 14$168,000$117,694$285,694
Year 15$180,000$138,811$318,811
Year 16$192,000$162,323$354,323
Year 17$204,000$188,402$392,402
Year 18$216,000$217,234$433,234
Year 19$228,000$249,017$477,017
Year 20$240,000$283,965$523,965
Year 21$252,000$322,308$574,308
Year 22$264,000$364,289$628,289
Year 23$276,000$410,173$686,173
Year 24$288,000$460,242$748,242
Year 25$300,000$514,797$814,797
Year 26$312,000$574,164$886,164
Year 27$324,000$638,689$962,689
Year 28$336,000$708,747$1,044,747
Year 29$348,000$784,737$1,132,737
Year 30$360,000$867,087$1,227,087

Frequently asked questions

How long does $1,000/month take to double at 7%?+

At 7% compound interest, money doubles approximately every 10.3 years (Rule of 72). So your investment would double at around year 10.3, and double again at year 20.6. Over your 30-year period, your contributions will approximately triple or more.

What if the interest rate changes on $1000/month at 7% for 30 years?+

Rate changes dramatically affect the final balance. At 5%, your 30-year result would be approximately $835,726 โ€” $391,361 less. At 9%, it would be approximately $1,844,474 โ€” $617,387 more. The difference grows exponentially over time.

How does monthly vs annual compounding affect the result?+

Monthly compounding (used here) produces slightly more than annual compounding at the same nominal rate. At 7% annually compounded, your 30-year result would be $1,227,087 โ€” compared to $1,227,087 with monthly compounding. The difference of $0 grows larger the longer the time horizon.

Adjust the scenario

Monthly contribution
$1,000/mo
Fixed for this scenario
7.0%
30 years
Adjusted result
$1,227,087
at 7% for 30 years
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