Effective Annual Rate Calculator
This effective annual rate calculator converts a nominal interest rate to EAR and shows how compounding frequency changes what you pay or earn.
What it does
The Effective Annual Rate Calculator converts a nominal (stated) interest rate into the real yearly rate you actually pay or earn once compounding is included. It shows how the same headline rate becomes larger the more often interest is added.
Data sources & parameters
This calculator uses standard financial formulas and runs entirely in your browser. It needs no external rate data — your result is computed only from the values you enter above.
We always strive to use the latest data for every variable so our results and reports are as accurate as possible. Even so, errors are possible — you should not rely on this tool or its report alone, and we accept no liability for any decision made based on it.
The formula
EAR = (1 + r/m)^m − 1, where r is the nominal annual rate and m the number of compounding periods per year
How it works
Enter the nominal annual rate and how many times a year interest compounds. The tool applies the rate per period, compounds it over the year, and reports the effective annual rate plus the difference from the nominal figure.
Where it is used
- Comparing savings accounts or loans quoted with different compounding frequencies
- Turning a monthly or daily rate into a true annual cost or yield
- Checking how much compounding adds on top of a headline rate
Worked example
A rate of 6% compounded monthly (12 periods) works out to an effective annual rate of …, which is … higher than the nominal figure.
What the effective annual rate calculator does
The effective annual rate calculator turns a nominal, or stated, interest rate into the effective annual rate you pay or earn once compounding is included. Banks, card issuers, and lenders usually quote a headline rate, and that number alone does not tell you how much interest accrues over a year.
Enter the nominal annual rate and the number of times interest is compounded each year, and the calculator reports the effective annual rate and the difference between the two. That difference is easy to overlook when comparing products that quote rates in different ways.
Nominal rate versus effective rate
If an account pays 6% a year, that 6% is the nominal rate. Most accounts and loans add interest monthly, quarterly, or even daily, not once at the end of the year. Each time interest is added, it joins the balance and starts earning interest of its own, so by the end of the year you have earned slightly more than a flat 6%.
The effective annual rate is the single yearly figure that already includes compounding, so it lets you compare two products on equal terms even when they compound at different frequencies.
The formula
EAR = (1 + r ÷ m) raised to the power of m, minus 1
Here r is the nominal annual rate written as a decimal, and m is the number of compounding periods in a year: 12 for monthly, 4 for quarterly, 365 for daily. Dividing the nominal rate by m gives the rate for a single period, and raising the term to the power of m compounds it across all the periods in the year.
For a 6% nominal rate compounded monthly, the monthly rate is 0.06 divided by 12, or 0.005. Raising 1.005 to the twelfth power and subtracting 1 gives about 0.0617, or 6.17%. The extra 0.17 percentage points is what compounding adds across the year.
How compounding frequency changes the rate
The more often interest compounds, the more times it is added and the sooner each addition begins earning. Daily compounding produces a higher effective rate than monthly, which in turn beats annual compounding.
With annual compounding the effective rate equals the nominal rate exactly, because interest is added only once. The jump from annual to monthly is noticeable, while the step from monthly to daily is smaller, because most of the effect is already captured once interest is added several times a year.
A slightly lower nominal rate that compounds daily can therefore cost or pay more than a higher nominal rate that compounds annually, and only the effective rate shows which.
How to use the calculator
- Enter the nominal annual rate quoted by the bank or lender.
- Enter how many times a year interest compounds: 12 for monthly, 4 for quarterly, 365 for daily, or 1 for annual.
The calculator shows the effective annual rate and the difference from the nominal figure, and the chart compares the two side by side.
Reading the results
Use the effective annual rate when comparing products. The difference line shows how much the quoted rate understates the effective one.
For savings, a higher effective rate means you earn more than the headline suggests. For borrowing, the same effect works against you: the effective rate is the cost of the debt, and it is always at least as high as the nominal rate. When a lender advertises a low nominal rate but compounds frequently, the effective rate shows the full cost.
Where EAR matters
- Two savings accounts may quote the same nominal rate but compound differently. The one that compounds more often has the higher effective rate and pays you more.
- Card interest is often quoted monthly. Converting it to an effective annual rate shows the yearly cost of carrying a balance.
- A monthly or daily rate means little on its own. The effective annual rate puts it on a standard yearly basis so you can weigh it against other options.
For savings, look for the higher effective rate; for debt, the lower one.
This article is general information only and is not financial advice.
About This Effective Annual Rate Calculator
Use this effective annual rate calculator to get an instant estimate based on the figures you enter. Adjust the inputs above to match your situation, or browse all our calculators to plan your next step.
Frequently asked questions
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