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Effective Interest Rate Calculator

Compare a nominal annual rate (APR) with the effective annual rate (APY). Choose a compounding schedule, convert in either direction and see the periodic rate when applicable.

Enter a rate from 0 to 1,000,000%. This is a mathematical rate conversion, not a lender’s legal APR disclosure or financial advice. Actual fees, payment timing, taxes and account terms can change the rate shown by a financial provider.

How do I convert APR to APY?

For periodic compounding, APY = (1 + APR ÷ m)^m − 1, where m is the number of compounding periods per year. To convert APY back to nominal APR, use APR = m × ((1 + APY)^(1/m) − 1). Continuous compounding uses APY = e^APR − 1. Enter rates as percentages; for example, 12 means 12%.

Frequently asked questions

How do I convert APR to APY?

For periodic compounding, APY = (1 + APR ÷ m)^m − 1, where m is the number of compounding periods per year. To convert APY back to nominal APR, use APR = m × ((1 + APY)^(1/m) − 1). Continuous compounding uses APY = e^APR − 1. Enter rates as percentages; for example, 12 means 12%.

Are my rates uploaded?

No. The conversion runs in this browser. Values are not uploaded or saved by this tool.

What APY is equivalent to 12% APR compounded monthly?

The effective APY is about 12.6825%. Each monthly period is 1%, and those monthly gains compound over the year.

Is this the same as the APR disclosed by a bank or lender?

Not necessarily. This tool converts a user-entered nominal annual rate using a selected compounding frequency. Legal APR disclosures may include fees, payment schedules or rules that this mathematical conversion does not model.