$100/Month at 7% for 30 Years → $121,997
Final portfolio value
$121,997
Total contributed
$36,000
Investment gains
$85,997
Total contributed: $36,000
Investment gains: $85,997
Investing $100 per month at 7% annual return for 30 years grows to $121,997. Total contributed: $36,000. Investment gains: $85,997. Free compound interest calculator.
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Frequently asked questions
How does compound interest work?
Compound interest earns returns on both your principal and previously earned interest. The formula is FV = P(1+r)ⁿ + PMT·((1+r)ⁿ-1)/r for regular contributions.
What is a realistic annual return for investing?
Historically, a diversified stock portfolio has returned 7-10% annually before inflation. 7% is a commonly used conservative estimate that accounts for inflation adjustment.
What is the Rule of 72?
Divide 72 by your annual return rate to estimate how many years it takes to double your money. At 7%, your money doubles in approximately 10.3 years.
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