Effective Rate Calculator

Convert nominal interest rate (APR) to effective annual rate (APY). Compare rates with different compounding.

Calculate effective annual rate from nominal rate.

About This Calculator

Compare interest rates accurately with the Effective Rate Calculator. The effective rate (APY) accounts for compounding, giving you the true cost or return of an investment.

Banks advertise APR (Annual Percentage Rate), but you actually earn or pay APY (Annual Percentage Yield). The more frequently interest compounds, the greater the difference between the two. Understanding this helps you compare financial products fairly.

Effective Rate Formula

APY = (1 + APR/n)^n - 1

Where n = number of compounding periods per year.

Practical Example

12% APR compounded monthly: APY = (1 + 0.12/12)^12 - 1 = 12.68%. On $10,000, that's $1,268 earned vs $1,200 with simple interest.

APR to APY Conversion

APRMonthlyDaily
5%5.12%5.13%
10%10.47%10.52%
12%12.68%12.75%
20%21.94%22.13%

Pro Tips

  • Compare savings accounts using APY, not APR
  • Credit card APR understates true cost
  • More frequent compounding = higher effective rate
  • Continuous compounding gives maximum effect

Related tools: Compound Interest Calculator for growth projections, Interest Calculator for loan costs, and Savings Calculator for account comparisons.

Frequently Asked Questions

How is effective rate calculated?

APY = (1 + APR/n)^n - 1, where n = compounding periods. 12% APR compounded monthly: (1 + 0.12/12)^12 - 1 = 12.68% APY. More compounding = higher effective rate.

What is the difference between APR and APY?

APR is simple annual rate. APY includes compounding effect. APY is always higher than APR (except annual compounding where they're equal). Compare savings using APY.

Why does compounding frequency matter?

More frequent compounding means interest earns interest sooner. Daily compounding at 5% APR = 5.13% APY. Monthly = 5.12% APY. The difference grows with higher rates.