APY stands for annual percentage yield, and it tells you how much interest you’ll actually earn on your money over one year, including the effect of compound interest. If you have a savings account, CD, or money market account, the APY is the single number that shows your real return. A traditional savings account at a big bank might offer 0.38% APY, while the best high-yield savings accounts currently pay up to 5.00% APY, so understanding this number can make a real difference in what you earn.
How APY Works
APY reflects not just the base interest rate on your account but also how often that interest compounds. Compounding means the bank calculates your interest, adds it to your balance, and then calculates future interest on that larger balance. The more frequently this happens, the more you earn, because each round of interest earns its own interest going forward.
Most savings accounts compound interest daily, which means every single day the bank takes your balance, calculates a tiny sliver of interest, and adds it in. A CD might compound monthly or quarterly instead. Two accounts could advertise the same base interest rate but produce different APYs because one compounds more frequently than the other. The APY captures that difference in a single, comparable number.
Here’s a practical example. Say you deposit $10,000 into an account with a 4.50% APY. After one year, you’d have roughly $10,450, assuming you didn’t add or withdraw money. That same $10,000 in an account paying the national average of 0.38% APY would earn about $38 over the same period.
The Formula Behind APY
Banks calculate APY using a standard formula: APY = (1 + r/n)^n − 1. In that formula, “r” is the nominal (or stated) interest rate, and “n” is the number of times interest compounds per year. For daily compounding, n equals 365. For monthly compounding, n equals 12.
You don’t need to memorize this formula. The important takeaway is that when you compare two accounts, comparing APY to APY gives you an apples-to-apples picture of your earnings. Comparing base interest rates alone can be misleading because it ignores compounding.
APY vs. APR
APY and APR (annual percentage rate) sound similar but work in opposite directions. APY is the number you want to see on accounts where you’re earning interest, like savings accounts and CDs. APR is the number attached to accounts where you’re paying interest, like credit cards, auto loans, and mortgages.
The key technical difference: APY includes the effect of compounding, while APR does not. APR accounts for certain fees but treats interest as if it’s calculated once a year. Banks advertise APY on savings products because compounding makes the number look higher and more attractive. Lenders advertise APR on loans because excluding compounding makes the borrowing cost look lower. Knowing which number you’re looking at helps you compare offers accurately.
What Counts as a Good APY
The national average APY on savings accounts sits at 0.38%, which is what you’ll typically find at large traditional banks. Online banks and credit unions routinely offer 10 to 13 times that rate. As of mid-2025, top high-yield savings accounts pay between 4.00% and 5.00% APY. CDs can offer similar or slightly higher rates, but they lock your money up for a set term.
Most high-yield savings accounts are variable rate, meaning the bank can adjust the APY at any time without advance notice. When the Federal Reserve cuts interest rates, these APYs tend to drop. When rates rise, they tend to follow upward. So the APY you see advertised today may not be the rate you’re earning six months from now.
How Banks Must Disclose APY
Federal rules under the Truth in Savings Act (known as Regulation DD) require banks to use the term “annual percentage yield” whenever they advertise a rate of return on deposit accounts. They can abbreviate it as “APY” after spelling it out once, but they can’t advertise a different rate more prominently than the APY.
When a bank advertises an APY, it also has to disclose several additional details:
- Variable rate notice: Whether the rate can change after you open the account.
- Time period: How long the advertised APY will last, or a statement that it’s accurate as of a specific date.
- Minimum balance: The minimum balance you need to actually earn the advertised APY. Some accounts offer tiered rates, paying higher APYs only on balances above certain thresholds.
- Minimum opening deposit: If you need to deposit more to open the account than you need to earn the APY, the bank must say so.
- Fees: A statement that account fees could reduce your earnings.
- Early withdrawal penalties: For CDs, the bank must disclose penalties for pulling money out before the term ends.
These disclosures exist so you can compare accounts on equal footing. If one bank advertises 5.00% APY but requires a $25,000 minimum balance and charges a monthly fee, while another offers 4.75% APY with no minimums and no fees, the second account could easily earn you more in practice.
How to Use APY When Choosing an Account
Start by comparing APYs directly, since the number already accounts for differences in compounding frequency. Then look at the conditions attached to that rate. A high APY loses its appeal if you can’t meet the minimum balance, if the rate is an introductory offer that drops after a few months, or if monthly maintenance fees eat into your earnings.
For savings you might need to access, a high-yield savings account with no withdrawal restrictions and a competitive APY is usually the most practical choice. For money you can set aside for a fixed period, a CD locks in a guaranteed APY for the full term, protecting you if rates drop. In both cases, look for FDIC or NCUA insurance, which protects your deposits up to $250,000 per depositor, per institution.