Compound Interest Calculator
See how savings grow with compounding and regular monthly contributions.
Your details
How the compound interest calculator works
The first term compounds your starting balance k times per year. The second term is a future-value annuity that compounds every monthly contribution from the moment it is deposited.
Formula
A = P(1 + r/k)^(kt) + PMT · ((1 + i)^n − 1)/i
Worked example
$10,000 plus $300 a month at 7% for 20 years grows to roughly $195,000, of which about $113,000 is interest.
Frequently asked questions
How often should interest compound?
More frequent compounding produces slightly more growth. The difference between monthly and daily compounding is small compared to the rate and time horizon.
Does this account for inflation?
No. To see real purchasing power, subtract expected inflation from your annual return before calculating.
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