Compound Interest Calculator
Growth with compounding and regular contributions.
- Total deposits
- $34,000.00
- Interest earned
- $20,713.58
- Effective annual rate
- 7.229%
How this calculator works
Interest is added to the balance at the chosen frequency, and later interest is earned on that interest. Monthly contributions are added at the end of each month.
Formula
A = P(1 + r/k)^(k·t) + contributions grown at the same rate
Example
$10,000 at 7% compounded monthly grows to about $20,097 in 10 years with no extra deposits.
When to use it
- Show the value of starting to save early
- Compare compounding frequencies
- Project a savings or brokerage account
Frequently asked questions
How often should interest compound?
More frequent compounding earns slightly more, but the gap between monthly and daily is small. The rate, your contributions and the time invested matter far more.
What is the rule of 72?
Divide 72 by the annual rate to estimate how many years money takes to double. At 8% a year, it doubles in about 9 years.
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