APY is the yearly interest rate you actually earn, including compound interest
APY stands for Annual Percentage Yield. It tells you how much money your savings account will earn over one year, accounting for the fact that interest gets added to your balance and then earns interest itself. If a savings account offers 4.50% APY, a $10,000 deposit will grow to $10,450 after one year (before any withdrawals or deposits).
Banks use APY instead of a simple interest rate because it shows the real return you get. The difference between APY and a basic interest rate matters most when interest compounds frequently—daily, weekly, or monthly. The more often interest is added to your account, the more you earn on that interest, and APY captures that full picture.
APY changes based on what the Federal Reserve does with interest rates. When the Fed raises rates, banks typically raise the APY they offer on savings accounts. When the Fed cuts rates, APY on new deposits falls. Your existing balance keeps earning at the rate you locked in, but new money deposited after a rate change earns the new rate.
Key Takeaways
- APY is the total interest you earn in a year, including the effect of compound interest added back to your account.
- A higher APY means your money grows faster, so comparing APY across banks helps you find the best return on savings.
- APY changes when the Federal Reserve adjusts interest rates, so the rate you see today may be different next month.
- Online banks typically offer higher APY than brick-and-mortar banks because their operating costs are lower.
- The difference between APY and a simple interest rate is small on monthly or quarterly compounding, but matters more with daily compounding.
How compound interest works inside APY
Compound interest means interest earns interest. If your account compounds daily, the bank calculates interest on your balance, adds it to your account, and then calculates tomorrow's interest on the new, larger balance. This cycle repeats every day of the year.
APY already includes all those compounding cycles in one number. You do not have to do the math yourself. A 4.50% APY account will earn exactly 4.50% over the year, no matter how often compounding happens behind the scenes. The bank has already done the calculation and expressed it as a single annual rate.
Without compound interest, a simple 4.50% rate would earn you $450 on $10,000. With daily compounding built into the APY, you earn slightly more because each day's interest gets added and starts earning its own interest. The difference is usually small—a few dollars on most balances—but it adds up over years.
Why APY varies between banks
Banks set APY based on what they pay to borrow money and what they charge to lend it out. When the Federal Reserve raises its benchmark rate, banks have more room to raise APY on savings accounts. When the Fed cuts rates, banks lower APY to protect their profit margins.
Online banks almost always offer higher APY than traditional banks. They have lower overhead—no branch buildings, fewer employees, no teller windows—so they pass savings to customers through higher rates. A brick-and-mortar bank might offer 0.01% APY while an online bank offers 4.50% APY on the same type of account.
Account type also matters. Money market accounts and high-yield savings accounts typically offer higher APY than regular savings accounts. Certificates of Deposit (CDs) often offer even higher rates, but you lock your money away for a set time. Checking accounts almost never earn meaningful APY.
How to compare APY across different banks
When you are shopping for a savings account, look at the APY number first. Ignore the bank's name or how many branches it has. The APY is what determines how fast your money grows. A 4.50% APY account will earn twice as much as a 2.25% APY account over the same time period.
Check whether the APY is may provide or promotional. Some banks offer a higher rate for the first few months, then drop it. The bank should disclose this in writing. If the rate is not labeled as promotional or introductory, assume it is the ongoing rate, but confirm before opening the account.
Also verify the minimum balance required to earn the stated APY. Some banks offer high rates only on balances above $25,000 or $100,000. Others have no minimum. A high APY on a balance you cannot reach is not useful to you.
What happens to your APY when rates change
The Federal Reserve does not set APY directly—it sets the federal funds rate, which is the rate banks charge each other to borrow overnight. Banks use this as a benchmark and adjust the APY they offer to customers. When the Fed raises rates, banks raise APY within days or weeks. When the Fed cuts rates, APY falls quickly.
Your existing balance keeps earning at the rate you locked in when you opened the account, unless the bank changes the terms. Banks can lower APY on existing accounts, but they must notify you in advance (usually 30 days). They cannot lower your rate without telling you first.
If your bank lowers APY and you do not like the new rate, you can move your money to another bank. There is no penalty for closing a savings account and transferring your balance elsewhere. Many people switch banks when rates drop to find a bank offering a higher APY.
APY versus interest rate: why the difference matters
An interest rate is the percentage the bank pays on your balance, usually stated as an annual rate but not accounting for compounding. An APY is that same rate plus the effect of compound interest. For most savings accounts, the difference is small—less than 0.10% in most cases—but it grows larger with higher rates and more frequent compounding.
Daily compounding produces a slightly higher APY than monthly or quarterly compounding. If a bank compounds interest daily, the APY will be a bit higher than if it compounds monthly, even if the base interest rate is the same. This is why APY is the better number to use when comparing accounts.
Banks are required to disclose APY prominently when advertising savings accounts. If you see a rate advertised, it should be the APY, not a simple interest rate. If a bank shows only an interest rate without the APY, ask for the APY before opening an account.
How much you actually earn at different APY levels
| Starting Balance | APY 1.00% | APY 2.50% | APY 4.50% | APY 5.00% |
|---|---|---|---|---|
| $1,000 | $10 | $25 | $45 | $50 |
| $5,000 | $50 | $125 | $225 | $250 |
| $10,000 | $100 | $250 | $450 | $500 |
| $25,000 | $250 | $625 | $1,125 | $1,250 |
These figures show the interest earned in one year with no additional deposits or withdrawals. The actual amount you earn depends on your balance and how long the money stays in the account. If you deposit money mid-year, you earn less. If you withdraw money, your balance shrinks and so does the interest.
The table assumes the APY stays constant for the full year. In reality, banks change APY frequently, so your actual earnings may differ. Use this table as a rough guide to understand how different rates affect your money, not as a prediction of what you will earn.
Frequently Asked Questions
Does APY change if I add more money to my savings account?
No. The APY rate stays the same. Your new deposits earn the same APY as your existing balance. However, if the bank changes the APY after you deposit new money, the new rate applies to your entire balance going forward, not just the new deposit.
What is the difference between APY and APR?
APY is for savings accounts and shows what you earn. APR (Annual Percentage Rate) is for loans and credit cards and shows what you pay. APY includes compound interest; APR typically does not. When borrowing, a lower APR is better. When saving, a higher APY is better.
Can a bank lower my APY without warning?
Banks can lower APY on existing accounts, but they must notify you at least 30 days in advance. You will receive a notice by mail or email. If you do not like the new rate, you can withdraw your money and move it to another bank without penalty.
Is APY may provide to stay the same for a year?
No. APY on savings accounts is variable, meaning it can change at any time (with advance notice). Only Certificates of Deposit (CDs) lock in a fixed APY for the full term. If you want a may provide rate, open a CD instead of a regular savings account.
How often is APY interest added to my account?
Most banks compound and add interest daily, though some do it monthly or quarterly. Daily compounding means you earn slightly more because interest gets added more often. The APY already accounts for this, so you do not need to track compounding yourself.