Effective Interest Rate Calculator
Convert a nominal rate to the effective annual rate (EAR/APY) for any compounding frequency — and see what $10,000 really earns.
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Currency: Amounts are calculated in the currency you select; this site does not convert between currencies and does not use live exchange rates.
What this tool does
Turns a nominal (stated) annual rate into the rate you actually experience once compounding is counted. Monthly compounding of a 6% nominal rate yields 6.17% effective; daily compounding yields 6.18%; continuous compounding is the ceiling at e^r − 1. This is the math behind APY on savings accounts and the true cost hidden inside APR quotes.
How to use the Effective Interest Rate Calculator
- Enter your figures in the fields above.
- Check the filing status, state and pay-frequency selections — they change the tables used.
- Read the headline result first, then the breakdown: it shows exactly which tax or amount produced each line.
- Change any input to compare scenarios; the result updates with the same dated tables shown on this page.
Formula
EAR = (1 + r/n)^n − 1; continuous: EAR = e^r − 1
- r
- Nominal annual rate as a decimal
- n
- Compounding periods per year
Worked example
6% compounded monthly is a 6.1678% effective rate — $616.78 of interest on $10,000 in a year, not $600.
Inputs
- Nominal annual rate (%)6
- Compounding frequencyMonthly
- Principal for the earnings check10000
Result
- Effective annual rate (EAR / APY)6.17%
- Interest on your principal in one year$616.78
- Compounding premium over the nominal rate0.17%
Effective rate of a 6% nominal rate
| Compounding | EAR |
|---|---|
| Annually | 6.0000% |
| Semiannually | 6.0900% |
| Quarterly | 6.1364% |
| Monthly | 6.1678% |
| Daily | 6.1831% |
| Continuously | 6.1837% |
Results explained
- Effective annual rate (EAR / APY)
- Growth over one full year including compounding — the rate to compare offers with.
- Compounding premium over the nominal rate
- Extra percentage points created purely by compounding frequency.
Frequently asked questions
The nominal rate ignores compounding within the year. The effective rate includes it, so it is the true one-year growth. They are equal only with annual compounding.
Yes — for deposit accounts APY is the effective annual yield, including compounding. That is why APY is always at least the stated rate.
At small rates, a little: 6% monthly beats annual by about 0.17 points. At credit-card rates it matters a lot — 24% compounded daily is 27.11% effective.
The limit as compounding becomes constant: EAR = e^r − 1. It is the maximum effective rate for a given nominal rate and is used heavily in finance theory.
Nominal = n × ((1 + EAR)^(1/n) − 1). For monthly compounding and a 6.17% APY, that returns the 6% nominal.