APY Calculator
Turn a nominal rate and compounding frequency into the true annual percentage yield, project a balance, or reverse solve the rate.
Calculate
The stated annual rate before compounding. Calculated in your browser as you type; nothing is uploaded.
Compounding frequency
Interest is added 12 times a year.
Project a balance(optional)
Leave either field blank to skip the projection and see the yield alone.
Assumes one constant rate and unbroken compounding. Use it to compare options, not as a forecast of any specific account.
| Year | Interest to date | Balance |
|---|---|---|
| 1 | 511.62 | 10,511.62 |
| 2 | 1,049.41 | 11,049.41 |
| 3 | 1,614.72 | 11,614.72 |
| 4 | 2,208.95 | 12,208.95 |
| 5 | 2,833.59 | 12,833.59 |
How to calculate APY
Enter the nominal rate
Type the nominal annual rate, the stated rate before compounding is applied.
Pick a compounding frequency
Choose daily, monthly, quarterly, annually, or continuous compounding and the APY updates instantly.
Project a balance
Optionally add a starting balance and a term in years to see the ending value and the interest earned.
Read or reverse the result
Read the APY, or switch to reverse mode to find the nominal rate a target APY requires.
Why use this tool
Five compounding frequencies
Compare daily, monthly, quarterly, annual, and continuous compounding and watch the APY shift as interest is added more often.
Reverse solve the nominal rate
Enter a target APY and the calculator works backward to the nominal rate needed at your chosen frequency.
Balance projection
Add a starting balance and a term to see the ending value, the interest earned, and a year-by-year table below.
Nominal versus effective
The result separates the stated nominal rate from the effective yield, so the lift added by compounding is never hidden inside one number.
Runs entirely in your browser
Everything is calculated on your device as you type; nothing is uploaded and there is no signup.
About this tool
Annual percentage yield, or APY, is the real return on a deposit once compounding is counted. Two accounts can quote the same nominal rate, yet the one that compounds daily pays more than the one that compounds once a year, because interest starts earning interest sooner. This calculator takes a nominal annual rate and a compounding frequency and returns the APY, also called the effective annual yield, the moment you type.
Enter 5% compounded monthly and the APY is about 5.12%; switch to daily and it edges up again; switch to annually and the APY equals the nominal rate exactly. Add an optional starting balance and a term in years and the calculator projects the ending value and the interest earned, with a year-by-year table. Reverse mode flips the question: give it the APY you want and it solves for the nominal rate that reaches it at your chosen frequency, which is handy when checking an advertised yield against a stated rate.
The calculator assumes one constant rate and unbroken compounding, so treat the output as a clean comparison rather than a forecast of any specific account. Rates can be positive or negative, and the frequency is fixed to real options so there is no divide-by-zero to worry about. Everything runs in your browser as you type and nothing is uploaded. For growth with regular deposits, the compound interest calculator adds monthly contributions, and the simple interest calculator shows the same rate without any compounding for contrast.
Frequently asked questions
- What is the difference between APY and the nominal rate?
- The nominal rate is the stated annual rate before compounding. APY is what you actually earn once interest compounds during the year, so it is equal to or higher than the nominal rate. The two match only when interest compounds once a year.
- How is APY calculated?
- For a set frequency, APY is (1 + nominal rate ÷ periods) raised to the number of periods, minus 1. For continuous compounding it is the exponential of the nominal rate, minus 1. Enter 5% compounded monthly and the APY is about 5.1162%.
- How do I find the nominal rate from an APY?
- Switch to reverse mode and enter the APY you want. The calculator solves for the nominal annual rate that produces that yield at your chosen compounding frequency, which is useful when comparing an advertised APY against a quoted rate.
- Does the compounding frequency change the APY much?
- Less than the rate itself, but the gap is real. At a 5% nominal rate, annual compounding yields 5%, monthly gives about 5.12%, and daily a touch more. The more often interest is added, the more it earns on itself.
- Can I use a negative rate?
- Yes. Negative nominal rates are accepted and the yield is computed the same way. The tool guards the edges, so a rate low enough to wipe out the balance within one period shows a friendly message instead of a broken number.
- Is my data uploaded anywhere?
- No. Everything runs in your browser; nothing is sent to a server. The rates and balances you type stay on your device.
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