APY is calculated by taking your annual interest rate and compounding it daily, weekly, or monthly — whichever schedule your bank uses
Annual Percentage Yield (APY) is the total interest you earn in a year, expressed as a percentage of your account balance. It accounts for compounding, which means you earn interest on your interest. A bank calculates APY by taking the stated interest rate, applying it to your balance at regular intervals (usually daily), and adding that earned interest back into your account so the next calculation includes it.
The formula banks use is: APY = (1 + r/n)^n − 1, where r is the annual interest rate and n is the number of compounding periods per year. If your bank compounds daily, n = 365. If it compounds monthly, n = 12. The result is always expressed as a percentage.
The key difference between APY and the stated interest rate is that APY includes the effect of compounding. A bank might advertise a 4.50% interest rate, but if that rate compounds daily, your actual APY will be slightly higher — often 4.60% or more. Banks are required to disclose the APY, not just the interest rate, so you can compare accounts fairly.
Key Takeaways
- APY includes compounding, so it is always equal to or higher than the stated interest rate.
- The more frequently your bank compounds (daily beats monthly), the higher your APY will be on the same stated rate.
- Banks must disclose APY on savings accounts, usually in the account terms or on the product page.
- You can compare APY across banks directly because it is a standardized calculation; comparing interest rates alone can be misleading.
How compounding works in practice
Compounding means your bank calculates interest on your balance, adds that interest to your account, and then calculates the next period's interest on the new, larger balance. The more often this happens, the more you earn.
Example: You deposit $10,000 in an account with a 4.80% annual interest rate, compounded daily. Your bank divides 4.80% by 365 days to get a daily rate of about 0.0131%. On day one, it calculates interest on $10,000 and adds roughly $1.31 to your account. On day two, it calculates interest on $10,001.31, earning you slightly more. By the end of the year, daily compounding has added up to an APY of approximately 4.92% — higher than the stated 4.80% rate.
If that same account compounded monthly instead, your APY would be lower, around 4.91%. The difference seems small, but on larger balances or over many years, it adds up. This is why the compounding frequency matters when you are choosing between accounts.
Why banks disclose APY instead of just the interest rate
The Truth in Savings Act requires banks to show you the APY so you can compare accounts on equal footing. Without this rule, a bank could advertise a 5.00% interest rate compounded monthly and another could advertise 4.95% compounded daily — and the second account would actually pay you more, but you would not know it without doing the math yourself.
APY is the standardized number. When you see it on a savings account, you are seeing the real annual return you will receive, accounting for compounding. This makes it the only number you need to compare between banks.
Banks also disclose the APY as of a specific date, usually the date you are viewing the account information. Interest rates change, so the APY you see today may not be the APY you earn next month. High-yield savings accounts, in particular, can change rates frequently.
The difference between APY and interest rate
The interest rate is the percentage your bank applies to your balance each compounding period. The APY is what you actually earn over a full year when compounding is included.
| Term | What it is | Example |
|---|---|---|
| Interest rate | The percentage applied per compounding period | 4.50% annual rate, compounded daily |
| APY | The total return after one year, including compounding | 4.60% (the actual amount you earn) |
On a $10,000 deposit, a 4.50% interest rate compounded daily results in an APY of about 4.60%. That means you earn approximately $460 in a year, not $450. The $10 difference comes entirely from compounding.
How to find the APY for your account
Your bank discloses APY in several places. Check your account's product page on the bank's website, your account agreement or terms and conditions, or your monthly statement. Some banks also show APY in your online banking dashboard.
If you cannot find it, call your bank or visit a branch and ask for the current APY on your specific account. Banks are required to provide this information. Make sure you ask for the APY, not the interest rate — they are different numbers.
Keep in mind that the APY shown is current as of that date. If your bank changes rates, the APY will change too. High-yield savings accounts often adjust rates weekly or monthly, so check back periodically if you want to know your current APY.
Why APY changes and what affects it
Your bank's APY moves based on the federal funds rate, which the Federal Reserve sets. When the Fed raises rates, banks typically raise the APY they offer on savings accounts. When the Fed lowers rates, banks lower APY. This can happen multiple times per year.
The compounding frequency also affects APY, but your bank chooses this and rarely changes it. Most savings accounts compound daily, which is the most favorable to you. Money market accounts and some savings accounts may compound monthly or quarterly.
Your account balance does not affect the APY rate itself — the rate is the same whether you have $100 or $100,000 in the account. However, some banks offer tiered rates where higher balances earn a higher APY. Check your account terms to see if this applies to you.
How to use APY to compare savings accounts
When you are looking at different banks, list the APY for each account side by side. The account with the highest APY will earn you the most money, assuming you keep the same balance for the same time period. Do not compare interest rates — always compare APY.
Remember that APY can change. A high-yield savings account might offer 4.85% APY today and 4.50% next month if the Fed cuts rates. If you are choosing between a traditional bank and a high-yield online bank, factor in that the online bank's rate may drop, but it is likely to stay higher than the traditional bank's rate even after a cut.
Also consider other account features: withdrawal limits, minimum balance requirements, and whether the bank is FDIC-insured. APY is the most important factor for earning money, but it is not the only factor in choosing an account.
Frequently Asked Questions
Is APY the same as interest rate?
No. Interest rate is the percentage applied per compounding period. APY is the total return after one year, including the effect of compounding. APY is always equal to or higher than the interest rate.
How often does my bank compound interest?
Most savings accounts compound daily, which is the most frequent and most favorable to you. Some accounts compound monthly or quarterly. Check your account agreement or ask your bank. The compounding frequency is usually listed near the APY.
Can I calculate APY myself?
Yes, using the formula APY = (1 + r/n)^n − 1, where r is the annual interest rate and n is the number of compounding periods per year. However, your bank is required to calculate and disclose it for you, so you do not have to do the math yourself.
Does a higher APY mean I will earn more money?
Yes, on the same balance for the same time period. A $10,000 deposit at 4.85% APY earns more than the same deposit at 4.50% APY. The difference grows larger with bigger balances and longer time periods.
What happens to my APY if interest rates fall?
Your bank will lower your APY. High-yield savings accounts often adjust rates within days or weeks of a Fed rate cut. Traditional bank savings accounts may take longer to adjust, and some may not lower rates as quickly as they raise them.