APR ignores compounding; APY includes it. For savings you want a high APY; for loans a low APR.

What formula does the APY Calculator use?

It calculates using APY = (1 + r/n)^n − 1. The guide above walks through what each part means with a worked example.

How accurate is the APY Calculator?

It uses standard, widely-accepted financial formulas, so the math is exact for the figures you enter. Real-world numbers can differ once lenders, taxes, fees and rounding are applied, so treat the result as a close estimate rather than a formal quote.

Does the APY Calculator include taxes and fees?

It includes only the fields shown on the form. Where inputs for extra costs (fees, taxes, insurance) are available, add them for a fuller picture — a real quote may still vary by provider.

Is this calculator free to use?

Yes — every GKCalculators calculator is 100% free with no sign-up required. Create a free account only if you want to save your calculation history across devices.

All calculations run instantly in your browser. Nothing is sent anywhere unless you tap ‘Explain my results’ (AI) or ‘Save’ while signed in.

Can I share my result?

Yes. Tap Share and we copy a link with your exact inputs baked in, so anyone who opens it sees the same result.

APY Calculator

Turn a nominal interest rate into the true annual percentage yield by compounding frequency.

Compare

Nominal interest rate %

Compounding frequency

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Annual Percentage Yield (APY)

5.116%

vs 5% nominal, compounded monthly

Nominal rate

5.00%

Effective (APY)

5.116%

AI Breakdown & Smart Takeaway

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How the APY Calculator works

The APY Calculator converts a nominal (stated) interest rate into the true Annual Percentage Yield by accounting for how often interest is compounded throughout the year — giving savers, investors, and borrowers an apples-to-apples number for comparing financial products.

APY turns a nominal rate into the real yearly yield after compounding, so you can compare savings accounts fairly.

Formula

APY = (1 + r/n)^n − 1

Pro tips

Always compare accounts by APY, not the headline nominal rate.

Key terms

Annual Percentage Yield (APY): — The real rate of return earned on a deposit account in one year, expressed as a percentage and fully accounting for the effect of compounding.
Nominal Interest Rate: — The stated or advertised annual interest rate before the effects of compounding are applied, also commonly called the APR on deposit products.
Compounding Frequency: — How often earned interest is added back to the principal balance within a year — common intervals include daily, monthly, quarterly, and annually.
Effective Annual Rate (EAR): — Synonymous with APY in most contexts; the true annualized rate that reflects compounding, used to compare products with different compounding schedules on equal footing.
Continuous Compounding: — A theoretical compounding scenario where interest is calculated and added to the principal at every infinitesimally small moment, yielding the mathematical maximum APY for a given nominal rate via the formula e^r − 1.
Principal: — The initial sum of money deposited or invested, which serves as the base on which interest is first calculated before compounding begins to grow the balance.