APY Calculator

An APY Calculator converts a stated interest rate into the effective annual yield based on the compounding frequency. It also projects the growth of a deposit over time, showing interest earned and ending balance. It is the standard way to compare deposit accounts that compound at different frequencies.

APY is calculated with the formula (1 + r/n)^n minus 1, where r is the stated annual rate as a decimal and n is the number of compounding periods per year. For example, a 4.5% rate compounded monthly produces an APY of approximately 4.59%. This tool applies the formula automatically.

The stated interest rate is the base rate before compounding. APY is the effective annual return after compounding is included. Because compounding increases the return, APY is always equal to or higher than the stated rate. The more frequently interest compounds, the larger the gap.

APY is used on the deposit side and reflects what a saver earns on an account. APR is used on the borrowing side and reflects the cost of credit, often including certain fees under the rules that apply to a given product. APY includes compounding in its calculation, while APR typically does not.

Yes, for a fixed stated rate, more frequent compounding produces a higher APY. The gain is largest when moving from annual to monthly compounding. The difference between weekly and daily compounding is very small. The calculator lets you see the exact effect for your rate and balance.

No. The projection shows gross growth and does not subtract account fees, taxes, or penalties. If your account charges a maintenance fee, subtract it from the projected interest to estimate your net return.

Yes. Enter the CD’s stated rate, its compounding frequency, and its term. The calculator will show the effective APY and the projected ending balance at maturity. If the CD compounds at a frequency different from the term length, the calculation handles the conversion.

The projection assumes a constant rate for the entire period. If your account has a variable APY, the actual result will differ. For variable-rate accounts, run the calculator with the current rate as a snapshot, and repeat with different rates to see a range of possible outcomes.

No. APY is a pre-tax measure. Interest earned in a taxable account is subject to income tax, which reduces the after-tax return. The projection shows gross growth only. For after-tax planning, subtract your expected tax on interest from the projected earnings.

The estimate is a close approximation when the inputs reflect the account terms. The APY formula used here matches the standard method required for deposit disclosures. The growth schedule applies interest at the compounding frequency you selected, with the final partial period prorated linearly. Projected balances may still differ slightly from a bank’s statement because of rounding conventions, day-count rules, and the exact timing of deposits.

The compounding formula used here applies broadly. However, disclosure rules and the exact definition of APY can vary by country. The calculator is built primarily around the U.S. Truth in Savings framework. If you are comparing accounts outside the United States, check whether the quoted yield uses the same compounding convention.

For a fixed stated rate, APY rises as compounding frequency increases but approaches a ceiling called continuous compounding. The formula for that ceiling is e^r minus 1, where e is the mathematical constant approximately equal to 2.71828. No finite compounding frequency can exceed that limit.