Glossary term
Effective Annual Interest Rate (EAR)
Effective annual interest rate is the true annual rate after accounting for compounding within the year.
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What Is the Effective Annual Interest Rate (EAR)?
The effective annual interest rate, or EAR, is the annual rate that reflects compounding within the year. It shows the actual yearly growth rate of a balance when interest is added more than once per year.
EAR is useful because two accounts or loans can quote the same nominal rate but compound at different frequencies. The more often interest compounds, the higher the effective annual rate, all else equal.
Key Takeaways
- EAR accounts for compounding within a year.
- It can differ from a stated or nominal annual rate.
- More frequent compounding raises EAR when the nominal rate is the same.
- EAR helps compare savings products, investments, and loan costs.
- Consumer disclosures may use related terms such as APY depending on the product and regulation.
Effective Annual Interest Rate Formula
r is the stated annual interest rate as a decimal. n is the number of compounding periods per year. The result is the effective annual rate after compounding.
EAR is especially useful when comparing products with the same stated rate but different compounding schedules. A monthly-compounded rate and a daily-compounded rate may look identical until converted to an effective annual basis.
Compounding Comparison
Compounding | What happens | Effect on EAR |
|---|---|---|
Annual | Interest added once per year | EAR equals nominal rate |
Monthly | Interest added 12 times | EAR is higher than nominal rate |
Daily | Interest added many times | EAR is slightly higher still |
No compounding | Simple interest only | EAR concept may not apply the same way |
A small difference in EAR can matter over long periods. Compounding effects accumulate, so the gap between stated and effective rates becomes more important as balances, time horizons, and rate levels increase.
For borrowers, the same math works in reverse. More frequent compounding can raise the effective cost of debt if all other terms are equal.
Limits and Misunderstandings
EAR focuses on compounding, not every cost. A loan's full cost may include fees, points, penalties, or required balances that are not captured by a simple EAR formula.
It is also different from APR and APY in disclosure contexts. APR is commonly used for credit costs, while APY is used for deposit yield disclosures. The right comparison depends on the product.
The Bottom Line
Effective annual interest rate turns a stated rate and compounding schedule into a true annual rate. It is helpful for comparing products, but fees and disclosure rules still need to be read carefully.