APY is the actual percentage of money you earn on your savings in a year, including the effect of compounding

APY stands for Annual Percentage Yield. It tells you how much interest your savings account will earn over twelve months, factoring in how often the bank compounds that interest. If a savings account offers 4.50% APY and you deposit $1,000, you will have roughly $1,045 after one year — though the exact amount depends on how the bank calculates and adds interest to your account.

APY differs from the interest rate itself because it accounts for compounding. Compounding happens when the bank adds interest to your account, and then calculates next month's interest on that larger balance. Over a year, this effect adds up. A bank might advertise an interest rate of 4.40%, but the APY could be 4.50% because of how often compounding occurs.

Banks are required by federal law to disclose APY prominently when you open an account or compare options. You will see it listed on the account terms, on the bank's website, and in any marketing materials. The APY you see is the rate that account will pay right now — but banks can and do change APY without notice, so the rate you lock in today may be different next month.

Key Takeaways

  • APY includes the effect of compounding, so it is always equal to or higher than the stated interest rate.
  • The more often a bank compounds interest — daily, weekly, or monthly — the higher the APY will be on the same stated rate.
  • Banks can change APY at any time, so the rate you see today is not may provide to stay the same.
  • APY is the single number you should use to compare savings accounts, because it reflects what you will actually earn.
  • The difference between a 4.00% APY account and a 5.00% APY account grows larger the longer your money sits in the account.

How compounding makes APY higher than the interest rate

The interest rate is the percentage the bank pays on your balance. Compounding is how often the bank adds that interest to your account and then pays interest on the new, larger balance.

Here is a concrete example. Suppose you have $10,000 in a savings account with a 4.80% interest rate, and the bank compounds interest daily. On day one, the bank calculates one day's worth of interest on $10,000 and adds it to your account — roughly $1.32. On day two, the bank calculates interest on $10,001.32, not $10,000. By the end of the year, you have earned more than 4.80% because you earned interest on the interest. The APY reflects that total: 4.91% instead of 4.80%.

The difference is small with daily compounding, but it matters. A bank that compounds monthly will show a lower APY than a bank that compounds daily, even if both offer the same interest rate. When you compare accounts, APY removes the guesswork — it is the number that already includes the compounding effect.

Why banks can change APY without warning

APY is not locked in. Banks adjust APY based on the Federal Reserve's interest rate decisions and their own business needs. When the Federal Reserve raises or lowers its benchmark rate, banks typically follow within days or weeks. When the Fed raised rates aggressively between 2022 and 2023, savings account APYs climbed from near zero to 4% and higher. When rates fall, APYs fall with them.

Your bank will notify you of a rate change, but you have no right to reject it or lock in the old rate. Some banks send an email or letter; others post the change on their website. The notification usually comes before the change takes effect, but the timing varies. If you want to keep earning a higher rate, you may need to move your money to a different bank offering better terms.

This is why comparing APY across banks matters. A bank offering 4.50% APY today might drop to 3.75% in three months if the Fed cuts rates. Shopping around every few months — especially after Fed announcements — can help you stay in an account that pays competitively.

The difference between APY and interest rate

The interest rate is what the bank promises to pay on your balance. APY is what you actually earn when compounding is included. Banks must disclose both, but APY is the number that matters for your decision.

A bank might advertise "4.40% interest rate, 4.50% APY." The 4.40% is the base rate. The 4.50% is what you earn because the bank compounds interest daily. If you compare two banks and one offers 4.40% APY while the other offers 4.50% APY, the second bank will put more money in your account over a year, even if the interest rates are close.

The gap between rate and APY grows larger the more frequently the bank compounds. Daily compounding produces a bigger gap than monthly compounding. Some banks compound continuously, which produces the largest possible APY for a given interest rate. When you see APY listed, you can ignore the interest rate — APY is the complete picture.

How to use APY to compare savings accounts

APY is the only number you need to compare how much different savings accounts will earn. Ignore marketing language, account names, and promotional offers. Look at the APY, check whether it applies to your balance size, and compare across banks.

Some banks offer different APYs for different balance tiers. A bank might pay 4.25% APY on balances under $25,000 and 4.50% APY on balances above that. Make sure the APY you are comparing applies to the amount you plan to deposit. A few banks offer promotional APYs for new customers — these are higher for a limited time, then drop to a standard rate. Read the fine print to see when the promotional period ends.

To find the best rate, visit bank websites directly or use savings account comparison tools that list current APYs. Rates change frequently, so a comparison from last month may be outdated. Online banks typically offer higher APYs than brick-and-mortar banks because they have lower overhead costs. Credit unions sometimes offer competitive rates as well, though you may need to be a member to open an account.

What happens to your money when APY changes

If your bank lowers APY, the money you already have in the account is not affected retroactively. You do not lose the interest you already earned. Going forward, new interest accrues at the new, lower rate. If you had $10,000 earning 4.50% APY and the bank drops to 3.75% APY, you keep the interest you earned at 4.50%, but next month's interest is calculated at 3.75%.

This is why rate changes matter most for money you plan to keep in the account for a long time. If you are saving for a goal a year away, a 0.75% drop in APY costs you roughly $75 on a $10,000 balance. If you are saving for retirement and plan to leave the money untouched for decades, rate changes compound into much larger differences. Moving your money to a higher-paying account takes a few days and costs nothing, so it is worth doing if your current bank's rate falls significantly behind competitors.

APY on different types of savings accounts

High-yield savings accounts offer the highest APYs because they are online-only and have minimal overhead. These accounts typically pay 4.00% to 5.00% APY, depending on the current interest rate environment. Traditional savings accounts at brick-and-mortar banks usually pay 0.01% to 0.50% APY — sometimes much less. The difference is substantial: $10,000 in a high-yield account earning 4.50% APY grows to $10,450 in a year, while the same amount in a traditional account earning 0.10% APY grows to only $10,010.

Money market accounts often pay APY rates similar to high-yield savings accounts, though they may require a higher minimum balance. Certificates of Deposit (CDs) lock your money away for a set term — three months, one year, five years — and pay a fixed APY for that entire period. CD rates are often higher than savings account rates because you cannot withdraw the money early without a penalty. If you know you will not need the money for a specific length of time, a CD with a higher APY can be a better choice than a savings account.

Frequently Asked Questions

Does APY mean I will definitely earn that percentage?

APY is the rate the bank is currently offering, but it can change at any time. You will earn that percentage only if the rate stays the same for the full year. If the bank lowers APY after three months, you earn the higher rate for those three months and the lower rate for the remaining nine months.

Is APY the same as interest?

No. Interest is the money the bank pays you. APY is the percentage rate used to calculate that interest, including compounding. If you earn $450 in interest on a $10,000 balance, the APY is 4.50%.

Why do online banks pay higher APY than traditional banks?

Online banks have lower costs because they do not operate physical branches. They pass those savings to customers by offering higher APYs. Traditional banks must maintain buildings and staff, so they keep more of their revenue and offer lower rates to savers.

Can I lock in an APY rate so it does not change?

No, not for savings accounts. Banks can change APY whenever they choose. Certificates of Deposit (CDs) do lock in a rate for a set term, but you cannot withdraw the money early without paying a penalty.

How often is interest added to my account if the bank compounds daily?

Daily compounding means the bank calculates and adds interest every day, but you typically see the total added once per month on your statement. The daily compounding still happens behind the scenes and increases your APY, even though you see it reflected monthly.