Banks pay interest by calculating a percentage of your account balance and depositing that amount into your account on a set schedule—usually monthly or daily, depending on the bank and account type.

The interest rate your bank offers is set by the bank itself, not by the government. Banks use the money you deposit to make loans to other customers and invest in securities. They keep most of the profit from those loans and investments, and they pay you a small portion as interest—your share of what they earned by using your money.

The amount you earn depends on three things: the interest rate the bank offers, how much money sits in your account, and how often the bank compounds the interest (meaning how often it calculates interest on your interest). A bank that compounds daily will pay you slightly more than one that compounds monthly, even if the stated rate is the same.

Key Takeaways

  • Banks calculate interest as a percentage of your balance and pay it on a schedule set by the bank—typically monthly, daily, or quarterly.
  • The interest rate varies by bank and account type; online banks often pay higher rates than brick-and-mortar banks because they have lower overhead costs.
  • Compounding frequency matters: daily compounding pays slightly more than monthly compounding at the same stated rate because interest earns interest.
  • You can find the exact rate and compounding method in your account's disclosure document, which banks must provide before you open the account.

How the Interest Rate Is Set

Each bank decides its own savings account interest rate. Banks are not required to offer any interest at all, though most do to attract deposits. The rate a bank offers depends on what the bank can earn by lending out your money, what competitors are offering, and how much the bank wants to grow its deposit base.

Banks do pay attention to the federal funds rate—the interest rate the Federal Reserve sets for banks to lend to each other overnight. When the Fed raises this rate, banks typically raise the rates they offer on savings accounts. When the Fed lowers it, savings rates usually fall. But the connection is not automatic or immediate; some banks move faster than others, and some move less than the Fed's change.

Online banks and credit unions often pay higher rates than traditional banks because they have fewer physical branches and lower operating costs. They can afford to pass more of their earnings to depositors. If you shop around, you may find rates that differ by 1 percent or more between banks.

How Interest Is Calculated

Banks use one of two main methods to calculate interest: simple interest or compound interest. Most savings accounts use compound interest, which means the bank calculates interest on your original balance plus any interest you have already earned.

Here is a concrete example. Suppose your bank offers 4.5 percent annual interest, compounded daily. Your account has $10,000. The bank divides the annual rate by 365 days to get a daily rate of about 0.0123 percent. Each day, it calculates interest on your current balance—including yesterday's interest—and adds it to your account. After one month, you might have earned about $37.50. After one year, you would have earned about $460, not $450, because of compounding.

The exact amount depends on the bank's compounding frequency. A bank that compounds daily will pay more than one that compounds monthly at the same stated rate. The difference is small for savings accounts but becomes larger the longer your money sits in the account.

When and How Banks Deposit Interest

Banks deposit interest on different schedules. Some deposit monthly, some quarterly, and some daily. The schedule is set by the bank and stated in your account disclosure document. You should see interest appear in your account on the same day each month (or quarter, or week) unless the bank changes its schedule, which is rare.

When interest is deposited, it becomes part of your account balance. If your bank compounds daily but deposits interest monthly, the bank is calculating interest on your interest every day, but you only see the total added to your account once a month. The next month's calculation starts from the new, higher balance.

You do not have to do anything to receive the interest. It is automatic. If your account is inactive or you have not made deposits in a long time, the bank still calculates and deposits interest on the balance that remains.

The Difference Between APR and APY

APR stands for annual percentage rate. APY stands for annual percentage yield. Banks must show you both numbers before you open an account. APR is the simple interest rate without compounding. APY includes the effect of compounding over one year.

If a bank offers 4.5 percent APR on a savings account with daily compounding, the APY might be 4.60 percent. The difference is the extra money you earn because interest compounds. For savings accounts, the difference is usually less than 1 percent, but it adds up over time. When you compare banks, use the APY number to get an accurate picture of what you will actually earn.

How to Find Your Bank's Interest Rate and Terms

Your bank's interest rate and compounding method are listed in the account disclosure document, sometimes called the Truth in Savings Act disclosure. Banks must give you this document before you open the account, and you can request it anytime. It shows the APR, the APY, how often interest is compounded, and when it is deposited.

You can also find current rates on your bank's website or by calling the bank directly. If you are shopping for a new account, compare the APY across several banks. A difference of 0.5 percent might not sound like much, but on a $50,000 balance, it means $250 more per year.

Your monthly or quarterly statement will show the interest you earned that period. If the amount seems wrong, check the disclosure document to confirm the rate and compounding method, then do the math yourself or contact the bank to ask how they calculated it.

What Happens to Interest If You Withdraw Money

If you withdraw money from your savings account, the bank recalculates interest based on your new, lower balance going forward. You keep all the interest you have already earned, but future interest is calculated on the smaller amount.

Some savings accounts have minimum balance requirements. If your balance falls below the minimum, the bank may stop paying interest, charge a fee, or close the account. Check your disclosure document to see if your account has a minimum. If it does and you are close to it, a withdrawal could cost you more in lost interest or fees than the money you are taking out.

Frequently Asked Questions

Do I have to pay taxes on savings account interest?

Yes. Interest earned on a savings account is taxable income. Banks send you a Form 1099-INT at the end of the year showing how much interest you earned. You report this on your tax return. The amount is usually small unless you have a large balance or a high interest rate, but it still counts as income.

Can a bank change my interest rate without warning?

Yes. Banks can change savings account rates anytime, and they do not have to give you advance notice for most accounts. Some banks notify customers of rate changes, but they are not required to. If your rate drops, you can move your money to another bank. This is one reason to shop around periodically.

Why do some banks offer much higher interest rates than others?

Online banks typically offer higher rates because they have lower operating costs than brick-and-mortar banks. They also use higher rates to attract deposits from customers who might otherwise bank elsewhere. Traditional banks with many physical branches have higher overhead and can afford to pay less interest.

What is the difference between a savings account and a money market account?

Money market accounts often pay higher interest rates than savings accounts, but they usually require a larger minimum balance and limit how many withdrawals you can make per month. Both are FDIC-insured up to $250,000. Choose based on whether you need frequent access to your money or can leave it untouched to earn more interest.

Does interest compound if I do not touch my account?

Yes. Interest compounds automatically whether you withdraw money or not. The bank calculates it on your balance and adds it to your account on its set schedule. You do not have to do anything for compounding to happen.