APY Calculator

By Ashley Kilroy | Updated July 16, 2026

An annual percentage yield or APY calculator can be a useful tool when you want to know a more accurate rate of return for a savings account, certificate of deposit, or other interest-bearing asset. Interest rates don’t always give the full picture because of an account’s compounding frequency. That frequency indicates how often your interest gets added in with the principal so it too can earn interest. By factoring in compounding, you can get a better idea of how quickly your balance might grow in one year.

An APY calculator, like the one below, can help you determine how an account may perform — all you have to do is input the required information. You can also use it to compare estimated rates of return on different accounts you may be considering. Here’s what to know about using an APY calculator.

*Actual interest credited by your financial institution may vary based on institution-specific calculation methodology.

Calculator Definitions

• Initial Deposit: The amount of money you first deposit into a financial account (you may also hear it referred to as the principal). Typically, a financial institution requires this for you to open the account (some may require a specific dollar amount). In addition, it becomes the basis for your interest earnings, with larger deposits earning more interest.

• Monthly Contribution: The amount of money you add to your account each month by making deposits. These contributions increase the principal amount upon which interest compounds.

• APY (Annual Percentage Yield): APY is the annualized rate of return, taking into account the effect of compounding throughout the time the account grows. Financial institutions provide the APY for accounts to show how the interest rate and compounding frequency work together to generate earnings.

APY lets you see how much your account will increase over one year. The more your account compounds, the more your balance grows. APY provides a more accurate measure than the interest rate of your account’s rate of return because it calculates the effect of compounding.

• Savings Time Period: The period (usually expressed in years) over which your initial deposit or investment will grow. This figure is a key factor for an APY calculator because it determines how long your account will earn interest. For instance, a $500 savings account compounding monthly with a 5.00% APY will earn $26 in interest after one year. On the other hand, letting the account sit for five years results in earnings of $142.

• Compound Frequency: Compounding refers to when your deposit earns interest. Financial products have different compounding rates, affecting how much you earn. For example, an account that compounds twice a year earns less than one that compounds every month (provided they have the same interest rate). The greater the compounding frequency, the more often you earn interest, increasing the account’s APY. Because interest generates returns on both your deposits and past interest earnings, frequent compounding has a snowball effect, allowing your interest to build upon itself.

• Interest Earned: This is the interest earned by your initial deposit and any subsequent deposits over a specific period. APY calculators use the interest on the initial amount and any previously earned interest to project your total earnings per year.

• Total Contributions: The sum of all the subsequent deposits made into the account. Financial institutions may limit your total contributions by account type (such as a CD allowing only the initial contribution) or by amount (such as a $1 million balance limit for savings accounts).

What Is APY?

As mentioned above, the APY (or Annual Percentage Yield), is a standardized measure that reflects the total amount of interest earned over one year. To add a little more detail:

• APY demonstrates the outcome of compounding interest after holding the account for one year.

• It is expressed as a percentage and provides a more accurate representation of the potential return than the interest rate, which expresses the percentage of interest you’ll earn on a deposit over a period of time, usually one year.

Because it involves multiple factors interacting over a one-year period, calculating APY can be challenging. Fortunately, an APY calculator makes understanding your account’s potential growth as easy as punching in some numbers.

How Do You Calculate APY?

You can calculate the APY yourself by using this mathematical formula:

APY = [1 + (r / n)]ⁿ – 1

You plug in your interest rate (r) expressed as a decimal and compounding frequency (n) expressed as a numeral, such as 12 for monthly. Then, you do the calculations.

For example, suppose you find a CD with a 5.00% interest rate compounding monthly. You use the APY formula to calculate your annual rate of return:

Formula: APY = [1 + (r / n)]ⁿ – 1

Step 1: [1+(.05/12)]¹² – 1

Step 2: [1+.00416667]¹² – 1

Step 3: 1.00416667¹² – 1

Step 4: 1.05116 – 1 = 0.05116, or 5.116%

Therefore, your APY is 5.116%. This number is slightly higher than the 5.00% interest rate thanks to the monthly compounding frequency.

FAQ

Is APY compounded daily, monthly, or yearly?

Whether your account compounds daily, monthly, or yearly depends on the specific account you have. However, the APY shows the rate at which your account will grow every year within compounding factored in. You can typically find your account’s compounding frequency by checking your deposit agreement or the disclosure forms.

What’s the difference between APY and APR?

APY, or annual percentage yield, expresses the rate of interest an asset would earn over a full year, thanks to compounding interest. APR (annual percentage rate), on the other hand, is the total rate of interest you would pay on a loan or a credit card, taking into account the interest rate and any other fees.

What is 5.00% APY on $1,000?

An account holding $1,000 with a 5.00% APY will yield different amounts based on the compounding period. For example, an account that compounds monthly will yield $51 at the end of the year for a total balance of $1,051.