Effective Annual Rate Calculator
See what a quoted interest rate really earns or costs over a year once compounding is included. Convert a nominal annual rate into the effective annual rate (EAR, also called APY or AER), or go the other way and find the nominal rate behind an effective rate.
Shows the interest for one year.
How to use the Effective Annual Rate Calculator
- Choose the direction: nominal to effective, or effective to nominal.
- Enter the rate as an annual percentage, for example 6 for 6%.
- Pick the compounding frequency, such as monthly for most loans and savings accounts or daily for many credit cards.
- Optionally enter an amount to see the interest for one year.
- Read the result and compare every compounding frequency in the table.
Effective annual rate formulas
- Nominal → effective: EAR = (1 + r ÷ n)n − 1
- Continuous compounding: EAR = er − 1
- Effective → nominal: r = n × [(1 + EAR)1/n − 1], or r = ln(1 + EAR) for continuous
Here r is the nominal annual rate as a decimal and n the number of compounding periods per year. Example: 6% compounded monthly: (1 + 0.005)12 − 1 = 0.06168 → 6.168%. On $10,000 that is $616.78 of interest in a year, compared with $600 at simple 6%.
Effective rate by compounding frequency
| Nominal rate | Annual | Quarterly | Monthly | Daily (365) | Continuous |
|---|---|---|---|---|---|
| 2% | 2.000% | 2.015% | 2.018% | 2.020% | 2.020% |
| 4% | 4.000% | 4.060% | 4.074% | 4.081% | 4.081% |
| 6% | 6.000% | 6.136% | 6.168% | 6.183% | 6.184% |
| 8% | 8.000% | 8.243% | 8.300% | 8.328% | 8.329% |
| 10% | 10.000% | 10.381% | 10.471% | 10.516% | 10.517% |
| 18% | 18.000% | 19.252% | 19.562% | 19.716% | 19.722% |
| 24% | 24.000% | 26.248% | 26.824% | 27.115% | 27.125% |
When comparing savings accounts or loans, compare effective rates (APY/AER), not nominal rates, because two offers with the same nominal rate can have different effective rates. On loans, also check the fees included in the APR.
Frequently asked questions
What is the effective annual rate formula?
EAR = (1 + r ÷ n)^n − 1, where r is the nominal annual rate as a decimal and n the number of compounding periods per year. For 6% compounded monthly: (1 + 0.06 ÷ 12)^12 − 1 = 6.168%. With continuous compounding EAR = e^r − 1 = 6.184%.
What is the difference between nominal rate and effective rate?
The nominal rate is the quoted annual rate before compounding. The effective rate includes the interest earned on interest during the year. They are equal only with annual compounding; more frequent compounding makes the effective rate higher.
Is EAR the same as APY?
Yes, in substance. APY (annual percentage yield) used by US banks, AER (annual equivalent rate) in the UK and EAR all describe the yearly rate including compounding. APR on loans is usually a nominal rate that may also include some fees, so APR and EAR are not the same.
How do I convert an effective rate back to a nominal rate?
Nominal rate = n × ((1 + EAR)^(1 ÷ n) − 1). An APY of 5% with monthly compounding corresponds to a nominal rate of 12 × (1.05^(1/12) − 1) = 4.889%. For continuous compounding, nominal = ln(1 + EAR).
Does daily compounding make a big difference?
Less than people expect. At 6%, monthly compounding gives 6.168%, daily gives 6.183% and continuous gives 6.184%. The gap grows with the rate: at 24% (typical of credit cards), monthly compounding gives 26.82% and daily 27.11%.
Why do banks use 365 days for daily compounding?
Most banks compound daily over 365 days a year (366 in leap years for some). A few use a 360-day convention. Choose daily (365) here; the 360-day result differs only slightly.