Last updated October 5, 2026 · Report an error
A nominal interest rate alone doesn't tell the whole story — how often it compounds changes the actual rate you earn or pay over a year, and the effective annual rate captures that true impact.
This calculator converts a nominal annual rate and compounding frequency into its effective annual rate.
How it works
Enter the nominal annual rate and how many times per year it compounds. The calculator applies the standard effective rate formula, which grows the rate by itself once per compounding period and compares the result to a full year.
- Enter nominal annual interest rate (%).
- Enter compounding periods per year.
- Click Calculate to see your results.
Examples
6% compounded monthly
A 6% nominal annual rate compounded monthly has an effective annual rate of about 6.1678% — slightly higher than the nominal rate due to compounding.
Who should use it
- Comparing savings accounts or CDs that compound at different frequencies.
- Understanding the true annual cost of a loan that compounds more often than annually.
Industry applications
- Banking and personal finance
- Investment and lending analysis
Advantages
- Applies the exact standard EAR formula for any compounding frequency.
- Makes differently-compounding rates directly comparable.
Limitations
- Doesn't account for fees — pair with an APR figure if fees are also part of the comparison.
Common mistakes to avoid
- Comparing two rates by their nominal values alone when they compound at different frequencies — always compare effective rates for an apples-to-apples comparison.
- Confusing EAR (a compounding-frequency effect) with APR (a fees-and-charges effect) — they aren't interchangeable.
Best practices
- When comparing savings accounts, CDs, or loans that compound at different frequencies, always compare their effective annual rates rather than their nominal rates.
Tips
- As compounding frequency increases toward "continuous" compounding, the effective rate approaches (but never exceeds) \(e^{r}-1\) — a useful theoretical upper bound for how much compounding frequency alone can boost a given nominal rate.