APY is the actual percentage of interest you earn in a year, including the effect of compounding

APY stands for Annual Percentage Yield. It tells you what percentage of your account balance you will earn as interest over one year, accounting for how often the bank compounds that interest. If a savings account offers 4.5% APY and you keep $10,000 in it for a full year without touching it, you will earn approximately $450 in interest (before taxes).

The key word is "yield"—it is what you actually get, not just what the stated rate looks like on paper. A bank might compound interest daily, weekly, or monthly. The more often it compounds, the more interest you earn on your interest, and the higher your APY climbs compared to the base rate. APY captures that compounding effect in a single number so you can compare accounts fairly.

APY changes. Banks adjust their rates based on what the Federal Reserve does with its benchmark rate. When the Fed raises rates, savings account APYs typically rise within days or weeks. When the Fed cuts rates, banks lower APYs. The rate you see today may not be the rate you earn six months from now.

Key Takeaways

  • APY includes the effect of compounding, so it is always equal to or higher than the base interest rate.
  • A higher APY means more money in your account at the end of the year, all else equal.
  • Banks change APY rates frequently, usually within days of a Federal Reserve decision.
  • Online banks typically offer higher APYs than brick-and-mortar banks because they have lower operating costs.
  • The difference between a 4.5% APY account and a 0.01% APY account on $10,000 is roughly $450 per year.

How compounding makes APY different from the base rate

The base interest rate is what the bank advertises as its rate. APY is what that rate becomes once compounding happens. Compounding means the bank pays you interest on your interest.

Here is a concrete example. Suppose a bank offers a 4.8% base rate, compounded daily. On day one, you have $10,000. The bank calculates one day's worth of interest (4.8% ÷ 365 days = 0.0131% per day) and adds it to your account—about $1.31. On day two, the bank calculates interest on $10,001.31, not just the original $10,000. That extra penny earns interest too. Over a full year, this daily compounding adds up. Your actual yield is 4.92% APY, not 4.8%.

The difference grows larger with higher rates and more frequent compounding. A 5.0% rate compounded monthly yields roughly 5.12% APY. The same 5.0% rate compounded daily yields roughly 5.13% APY. Banks are required to disclose APY so you can see the real number without doing the math yourself.

Why APY matters when comparing savings accounts

Two banks might advertise similar-sounding rates, but their APYs can differ because they compound at different intervals. Bank A offers 4.5% compounded monthly. Bank B offers 4.5% compounded daily. Bank B's APY will be slightly higher because daily compounding generates more interest-on-interest. When you are deciding where to put your money, APY is the number that tells you which account actually pays more.

Over a year, the difference between accounts might seem small—a few dollars on a modest balance. But on larger amounts or over multiple years, it compounds into real money. On $50,000 at 4.5% APY versus 0.5% APY, you earn roughly $2,000 more per year in the higher-rate account. That is money you do not have to earn elsewhere.

APY also lets you compare savings accounts to other places your money could go—money market accounts, certificates of deposit (CDs), or even checking accounts that pay interest. Each product will have its own APY. You can line them up and see which one pays the most for the same risk level.

How banks set and change APY rates

Banks do not set APY independently. The Federal Reserve sets a target range for the federal funds rate—the rate at which banks lend to each other overnight. When the Fed raises or lowers that rate, banks adjust the APY they offer on savings accounts to stay competitive and manage their own costs.

When the Fed raises rates, banks raise savings account APYs quickly because they want to attract deposits. When the Fed cuts rates, banks lower APYs more slowly because they are less eager to lose deposits. This is why you might see savings rates climb fast during a rate-hiking cycle but fall more gradually when rates are falling.

Online banks tend to offer higher APYs than traditional banks because they have fewer physical branches and lower overhead costs. They can afford to pass more of their earnings to depositors. During periods of high Fed rates, online banks often lead the market in APY offerings.

What APY does and does not tell you

APY tells you the interest rate you will earn, assuming you leave your money untouched for a full year. It does not tell you whether the bank is safe, whether it has good customer service, or whether you will have straightforward access to your money. Those are separate decisions.

APY also assumes the rate stays the same for the full year, which it usually does not. If you open an account at 4.5% APY and the Fed cuts rates three months later, your APY will likely drop. You do not earn 4.5% for the full year—you earn 4.5% for a few months, then a lower rate for the rest of the year.

Some accounts, like CDs, lock in an APY for a set term—six months, one year, five years. If you break the CD early, you pay a penalty. Savings accounts and money market accounts usually let you withdraw money anytime without penalty, but their APY can change at any time.

The relationship between APY and inflation

APY tells you how much your account balance grows in percentage terms, but it does not account for inflation—the rising cost of goods and services. If your savings account earns 4.5% APY but inflation is running at 3.5%, your money is gaining purchasing power at roughly 1% per year (the difference between the two). If inflation is higher than your APY, your money is actually losing purchasing power even though the account balance is growing.

This is why the APY environment matters. During periods when the Fed keeps rates high, savings accounts can earn more than inflation, and your money grows in real terms. During periods when rates are low, savings accounts may not keep pace with inflation, and you lose ground. Checking the current APY and comparing it to the current inflation rate gives you a sense of whether a savings account is protecting your money's value or eroding it.

How to find the APY on a specific account

Banks disclose APY in the account's terms and conditions, usually on the product page of their website. Look for a section labeled "Interest Rate and APY" or "Rate Information." The APY will be listed as a percentage, often with a note about when it was last updated.

Some banks show APY prominently at the top of the page. Others bury it in fine print. If you cannot find it on the main product page, check the full disclosure document—usually a PDF labeled "Account Terms" or "Deposit Account Agreement." The APY must be disclosed there by law.

When comparing accounts across different banks, make sure you are looking at APY, not the base rate. Some banks advertise the base rate in large text and the APY in smaller text, hoping you will focus on the bigger number. Write down the APY for each account you are considering, then compare them side by side.

Frequently Asked Questions

Does APY change if I withdraw money from my savings account?

The APY itself does not change—it is the rate the bank offers. But your earnings will be lower because you have less money in the account. If you withdraw $5,000 mid-year, you earn interest only on the remaining balance for the rest of the year. The APY rate stays the same; your actual interest earned goes down.

Is APY the same as interest rate?

No. Interest rate is the base percentage the bank pays. APY is the actual yield after compounding is factored in. APY is always equal to or higher than the interest rate. When comparing accounts, use APY because it shows what you actually earn.

Can I lock in an APY so it does not go down?

Not with a regular savings account—the APY can change anytime. With a CD (certificate of deposit), you lock in an APY for a set term, like one year or five years. If you keep the money in the CD until maturity, you earn that APY for the full term. If you withdraw early, you pay a penalty.

What is a good APY for a savings account right now?

APY changes frequently based on Federal Reserve decisions. Online banks typically offer the highest rates. Check current rates on banking comparison websites or directly on bank websites to see what is available today. Compare the APY to the current inflation rate to see whether your money is gaining or losing purchasing power.

How much interest will I earn if I deposit $5,000 at 4.5% APY?

Approximately $225 in one year (4.5% of $5,000). The exact amount depends on how often the bank compounds interest and whether you add or withdraw money during the year. Your bank statement will show the precise amount earned.