The Short Answer
APY stands for Annual Percentage Yield. It’s the real rate of return you earn on money in a savings account, CD, or money market account over one year — including the effect of compounding. Because it accounts for interest earning interest, APY gives you a more accurate picture of what you’ll actually earn than the plain interest rate does.
When you’re comparing savings accounts, APY is the number that matters. The higher the APY, the more your money grows.
APY vs. the Interest Rate
It’s easy to confuse APY with the interest rate, but they’re not the same. The interest rate is the base percentage a bank pays you. APY takes that interest rate and factors in how often the interest compounds — daily, monthly, or annually.
Compounding means you earn interest not just on your original deposit, but also on the interest you’ve already earned. The more frequently interest compounds, the higher the APY will be for the same stated interest rate.
Example: Two accounts both advertise a 5% interest rate. Account A compounds annually; Account B compounds daily. Account A’s APY is exactly 5.00%. Account B’s APY is about 5.13% — slightly higher because the daily compounding lets the interest start earning interest sooner. On a $10,000 balance, that’s roughly $513 versus $500 in a year.
APY vs. APR
These two acronyms look similar and are easy to mix up, but they describe opposite sides of your finances:
- APY (Annual Percentage Yield) — what you earn on money you save or invest, with compounding included
- APR (Annual Percentage Rate) — what you pay to borrow money, such as on a credit card or loan; it typically does not include compounding
A simple way to remember it: you want a high APY on your savings and a low APR on your debt.
How APY Is Calculated
You don’t need to do the math yourself — banks are required by federal law (the Truth in Savings Act) to disclose the APY so you can compare accounts on equal footing. But it helps to understand what drives the number.
The formula is: APY = (1 + r/n)n − 1, where r is the interest rate and n is the number of times interest compounds per year. The key takeaway is that more frequent compounding produces a higher APY, even when the underlying interest rate is identical.
Why APY Matters When Choosing an Account
When you shop for a savings account, the advertised APY lets you compare offers directly. A high-yield savings account at an online bank might offer an APY several times higher than a traditional brick-and-mortar bank’s savings account.
Example: A traditional bank might pay 0.40% APY, while an online high-yield account pays 4.50% APY. On a $20,000 emergency fund, that’s the difference between earning about $80 and about $900 in a year — for the exact same money sitting in the bank.
A Few Things to Watch For
- APY can change. Most savings and money market account APYs are variable — they rise and fall with market interest rates. A CD, by contrast, locks in its APY for the full term.
- Introductory rates. Some accounts advertise a high promotional APY that drops after a few months. Read the fine print.
- Balance requirements. Certain accounts only pay the top APY above a minimum balance, or cap the high rate at a certain dollar amount.
- Fees can erode earnings. A monthly maintenance fee can wipe out the interest a high APY would otherwise earn.
The Bottom Line
APY is the most honest measure of what your savings will earn because it includes compounding. When comparing savings accounts, CDs, or money market accounts, look at the APY rather than the plain interest rate — and remember that you want APY high on what you save and APR low on what you borrow.
Frequently Asked Questions
Is a higher APY always better?
For savings, generally yes — a higher APY means more earnings. But check for conditions like minimum balances, fees, or promotional rates that expire. The true value is the APY you’ll actually earn on your balance after any fees.
Does APY change over time?
For most savings and money market accounts, yes. These rates are variable and move with the broader interest rate environment. CDs lock in a fixed APY for the entire term, so they don’t change until the CD matures.
What’s the difference between APY and interest rate?
The interest rate is the base percentage the bank pays. The APY includes the effect of compounding, so it reflects your true annual return. The APY is always equal to or higher than the stated interest rate.
Why do online banks offer higher APYs?
Online banks have lower overhead than banks with physical branches, so they can pass those savings on to customers in the form of higher APYs. Their accounts are typically FDIC-insured just like traditional banks.
Is APY taxed?
The interest you earn (which the APY measures) is generally taxable as income. Your bank will send you a Form 1099-INT if you earn $10 or more in interest during the year, and you report it on your tax return.
Can APY be guaranteed?
Only for fixed-rate products like CDs, where the APY is locked for the term. Savings and money market account APYs are variable and can change at any time at the bank’s discretion.