About the Effective Interest Rate Calculator
A loan or savings account quotes a nominal yearly rate, but the rate you really pay or earn depends on how often interest is added. When interest is added more than once a year, interest earns interest, and the true yearly rate, called the effective annual rate (EAR) or annual percentage yield (APY), is higher than the nominal rate. This calculator converts a nominal rate to the effective rate for any compounding schedule from yearly to daily and continuous, and converts an effective rate back to the nominal rate that would produce it. An example amount shows what the difference means in money.
Updated October 2026
How to use the Effective Interest Rate Calculator
- 1Choose whether you want the effective rate or the nominal rate.
- 2Enter the rate as a percentage.
- 3Choose how often interest is added, from yearly up to daily or continuously.
- 4Optionally enter an example amount to see what it grows to.
- 5Read the answer and how far it differs from the quoted rate.
Why it matters when you choose a product
Two savings accounts can both advertise 4 percent but pay it differently: one compounds monthly and the other once a year. The effective rate shows that the first is slightly better. For loans, the reverse applies, because a loan that compounds more often costs more. Converting everything to an effective annual rate lets you compare products fairly.
Examples at a nominal 12 percent
- Yearly: 12.000% effective
- Quarterly: 12.551% effective
- Monthly: 12.683% effective
- Daily: 12.747% effective
- Continuous: 12.750% effective
Related tools
Use the Compound Interest Calculator to see growth over many years, the CD Calculator for fixed deposits, the APR Calculator for loans with fees, the Interest Rate Calculator to find an unknown rate, and the Simple Interest Calculator for interest that is not compounded. This tool is for information and is not financial advice.
Features
- Nominal to effective rate and back
- Yearly, six-monthly, quarterly, monthly, weekly and daily compounding
- Semi-monthly and fortnightly options
- Continuous compounding
- Money example for one year
- Difference in percentage points
- Runs in your browser
Frequently asked questions
What is the effective annual rate?
It is the yearly rate you really get once compounding is included. It equals (1 plus the nominal rate divided by the number of periods) raised to the number of periods, minus 1. A nominal 12 percent compounded monthly has an effective annual rate of about 12.683 percent.
What is the difference between APR and APY?
APR is the nominal yearly rate without compounding, and APY or EAR is the effective rate with compounding. Savings accounts usually advertise APY because it looks higher, while loans advertise APR because it looks lower. Always compare like with like.
How does compounding frequency change the effective rate?
More frequent compounding raises the effective rate, but with diminishing returns. At a nominal 10 percent, yearly compounding gives 10.000 percent, monthly gives 10.471, daily gives 10.516, and continuous compounding gives 10.517. The gains shrink as the frequency rises.
What is continuous compounding?
It is the limit as interest is added more and more often. The effective rate becomes e raised to the nominal rate, minus 1. It is used in some financial models and in physics and biology for smooth growth. Most real accounts compound at most daily.
How do I find the nominal rate from the effective rate?
Take (1 plus the effective rate) to the power of 1 over n, subtract 1 and multiply by n, where n is the number of periods a year. Choose the nominal option in the tool to do it. For an effective 12.6825 percent with monthly compounding, the nominal rate is 12 percent.
Does this include fees?
No. Fees, taxes and charges are separate. For a loan that includes fees, use the APR Calculator, which finds the true cost including upfront charges.