Important Note : This calculator estimates APY and compound-interest growth from the APR, starting balance, term, and compounding frequency entered. It does not include account fees, taxes, withdrawals, deposits, promotional rate changes, minimum-balance rules, or variable-rate changes.

Use this APY Calculator to estimate annual percentage yield, final balance, interest earned, and total return from an initial balance, APR, term, and compounding frequency. It is useful for comparing savings accounts, CDs, money market accounts, and other interest-bearing products where compounding affects the actual return.

Reviewed by: AjaxCalculators Editorial Team
Last updated: April 26, 2026
Method source: Standard APY and compound-interest formulas using APR, compounding frequency, principal, and term
Editorial standards: AjaxCalculators Editorial Policy

What This APY Calculator Calculates

This calculator estimates:

• APY, or annual percentage yield
• Final balance
• Interest earned
• Total return
• Term in years
• Compounding frequency
• Calculation details

The live tool uses your initial balance, APR, term, and compound frequency. It supports yearly, half-yearly, quarterly, monthly, weekly, and daily compounding.

What APY Means

APY stands for annual percentage yield. It represents the effective yearly return after compounding is included.

APR and APY can look similar, but they are not always the same. APR is the stated annual rate before the effect of compounding. APY shows the annual yield after interest is compounded. When interest compounds more often, the APY is usually slightly higher than the APR, assuming the same nominal rate.

How the APY Calculator Works

1) APY Formula

The standard APY formula is:

APY = (1 + r ÷ n)ⁿ − 1

To show APY as a percentage:

APY % = [(1 + r ÷ n)ⁿ − 1] × 100

In this formula:

• r is the APR as a decimal
• n is the number of compounding periods per year
• APY is the effective annual yield after compounding

2) Compound Balance Formula

To estimate the final balance over a selected term, the calculator uses compound growth:

Final balance = P × (1 + r ÷ n)^{n × t}

In this formula:

• P is the initial balance
• r is the APR as a decimal
• n is the number of compounding periods per year
• t is the term in years

3) Interest Earned

Interest earned is the difference between the final balance and the starting balance.

Interest earned = final balance − initial balance

4) Total Return

Total return shows the interest earned compared with the initial balance.

Total return = interest earned ÷ initial balance × 100

APY is an annualized yield. Total return depends on how long the money stays invested or deposited.

Compounding Frequency Used by the Calculator

The compounding frequency changes how often interest is added to the balance.

More frequent compounding generally increases APY because interest is added to the balance more often and can begin earning interest itself.

APY vs APR

APR is the stated annual percentage rate before compounding is fully reflected.

APY is the effective annual yield after compounding is included.

For example, a 5% APR compounded yearly gives an APY of 5%. But a 5% APR compounded monthly gives an APY slightly above 5% because interest is added throughout the year.

Assumptions and Important Notes

• This calculator assumes a fixed APR during the selected term.
• It assumes interest compounds at the selected frequency.
• It assumes no additional deposits or withdrawals during the term.
• It does not include account fees, taxes, penalties, or promotional conditions.
• It does not account for variable APY changes over time.
• It does not include early withdrawal penalties for CDs or time deposits.
• It assumes interest remains in the account and continues compounding.

Worked Example

Suppose you deposit $10,000 at a 5% APR for 1 year, compounded monthly.

Step 1: Convert APR to decimal
5% = 0.05

Step 2: Identify compounding periods
Monthly compounding means n = 12

Step 3: Calculate APY
APY = (1 + 0.05 ÷ 12)¹² − 1
APY ≈ 0.05116

Step 4: Convert to percentage
0.05116 × 100 ≈ 5.12%

Step 5: Estimate final balance
Final balance = 10,000 × (1 + 0.05 ÷ 12)^{12 × 1}
Final balance ≈ $10,511.62

Step 6: Find interest earned
Interest earned = 10,511.62 − 10,000 = $511.62

So, a $10,000 deposit at 5% APR compounded monthly would have an APY of about 5.12% and earn about $511.62 in one year before fees, taxes, or withdrawals.

How to Use This APY Calculator

1. Enter your initial balance.
2. Enter the APR as a percentage.
3. Enter the term in years and months.
4. Select the compounding frequency.
5. Click Calculate.
6. Review the APY, final balance, interest earned, total return, and calculation details.

How to Interpret the Result

APY shows the effective annual yield after compounding.

Final balance is the estimated account value at the end of the selected term.

Interest earned is the estimated amount gained above the starting balance.

Total return shows the total gain over the selected term as a percentage of the initial balance.

Term in years shows how the entered years and months are converted into a single time value for the compound-interest calculation.

Why APY Matters

APY helps compare accounts with different compounding schedules. Two accounts may advertise the same APR, but if one compounds daily and the other compounds yearly, the daily-compounding account may produce a slightly higher APY.

APY is especially useful when comparing:

• savings accounts
• high-yield savings accounts
• certificates of deposit
• money market accounts
• interest-bearing checking accounts

Common Mistakes to Avoid

• Do not confuse APR with APY.
• Do not compare accounts by APR alone when compounding frequencies differ.
• Do not ignore monthly fees or withdrawal penalties.
• Do not assume a promotional APY will last for the full term.
• Do not assume variable APYs will remain unchanged.
• Do not treat APY as after-tax return.
• Do not enter APY in the APR field unless the calculator specifically asks for APY.

APY Formula Summary

References

1. AjaxCalculators live APY Calculator
2. Consumer Financial Protection Bureau: Annual Percentage Yield calculation rules
3. FDIC: Compound Interest
4. Investor.gov: Compound Interest Calculator
5. Investopedia: Annual Percentage Yield definition and formula

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Disclaimer: This calculator is for educational and planning use only. It estimates APY and compound-interest growth from the values entered. Actual account earnings can vary because of fees, taxes, penalties, minimum-balance rules, rate changes, promotional terms, withdrawals, deposits, and financial institution policies. This calculator does not provide financial, investment, tax, or legal advice.