What APY means

Annual Percentage Yield, usually shortened to APY, is an annualized measure of the interest paid on a deposit account. It incorporates the account's interest rate and how frequently interest compounds. In plain language, APY estimates the percentage your deposited money could earn over a year when interest stays in the account and begins earning interest of its own.

APY commonly appears with savings accounts, money market deposit accounts, and certificates of deposit. Federal rules standardize the measure so consumers can compare the earning potential of covered deposit accounts even when institutions use different compounding schedules.

APY is different from APR. APY generally describes interest earned on deposits and reflects compounding. APR generally describes the annual cost of credit. An APY should not be entered as the APR for a debt simply because both are annual percentages.

How compounding changes the yield

An account's stated interest rate does not reflect compounding. APY does. Compounding occurs when credited interest is added to the account balance and can contribute to later interest calculations.

For an illustrative example, consider $1,000 left untouched for one year at a 5 percent interest rate compounded monthly. Each month, interest is calculated on a balance that may include earlier interest. With no withdrawals, fees, or rate changes, the balance would grow to about $1,051.16. The stated rate is 5 percent, while the APY is about 5.12 percent.

More frequent compounding can produce a somewhat higher APY when the stated rate is the same. The difference may look small over one year, but it can become more noticeable with a larger balance or more time. The comparison only works when the accounts otherwise have comparable terms.

APY is an assumption, not a promise

APY is useful because it applies standardized assumptions. For an account without a stated maturity, the calculation generally assumes the principal and interest remain deposited for 365 days and that no other transactions occur. Those assumptions create a common comparison, not a forecast of every account holder's actual earnings.

Your dollar earnings may differ because of:

  • Deposits or withdrawals during the year.
  • A variable interest rate that rises or falls.
  • Minimum-balance rules or balance-based rate tiers.
  • Monthly maintenance or transaction fees.
  • An early withdrawal and penalty on a certificate of deposit.
  • Interest credited on a schedule that affects when funds are available.

APY reflects interest, not every benefit or cost associated with an account. For example, a promotional cash bonus is separate from the APY. Fees can also reduce the amount you keep even though they are not subtracted from the advertised APY.

APY and APY earned

An advertised APY describes the account under the disclosure assumptions. A periodic statement may instead show an "annual percentage yield earned." That figure annualizes the relationship between interest actually earned during the statement period and the relevant balance for that period.

The APY earned on a statement may differ from the advertised APY if the rate changed, the balance moved during the period, or the account did not meet a condition for the advertised yield. It is also annualized, so it should not be read as the percentage actually added during that shorter statement period.

Comparing deposit accounts

Start with APY when comparing the earning rates of similar deposit accounts, then examine the conditions behind it. Check whether the rate is fixed or variable, how long it lasts, whether different balance tiers receive different yields, and what minimum balance is needed. Review maintenance fees and limits on accessing the money. For a certificate of deposit, also review the maturity date, renewal terms, and early-withdrawal penalty.

A higher APY may produce more interest under the same balance and timing assumptions, but it does not automatically make an account more suitable. Access, fees, insurance eligibility, rate stability, and account rules can matter as much as the headline yield. The institution's account disclosure controls the actual terms.

How APY relates to EastStar

EastStar accepts APY when you add a savings account or create a savings scenario. It treats APY as an effective annual yield, converts it into an equivalent monthly growth rate, and applies that rate to the projected balance. The planned monthly contribution is added after the projected growth for each month.

This model powers the savings-growth forecast on the dashboard. It also helps estimate the monthly contribution required for a savings goal or scenario with a target amount and date. When several saved accounts appear in the dashboard forecast, EastStar projects each account using its own balance, APY, and planned contribution, then combines their projected balances.

The projection assumes each entered APY and monthly contribution stay constant. It does not model an institution's exact daily balance calculation or interest-crediting schedule. It also does not anticipate variable-rate changes, fees, taxes, withdrawals, or deposits other than the planned monthly amount. Update an account when its APY, balance, or contribution changes so future projections use the newer assumptions.

For a step-by-step explanation of using an account balance, amount to save, and target date together, see Savings Goals.

Use the APY field for a savings yield and the APR field for a debt's borrowing rate. EastStar's projections are planning estimates; the bank, credit union, lender, or servicer records control actual earnings and costs.