Interest is money the bank pays you for letting them use your deposits

When you put money in a savings account, the bank lends that money to other customers—for mortgages, car loans, business lines of credit. The bank keeps the difference between what it pays you and what it charges borrowers. That payment to you is interest. The bank calculates it as a percentage of your balance, expressed as an annual rate, and deposits it into your account on a schedule set by the bank (usually monthly or daily).

The amount you earn depends on three things: how much money sits in the account, what interest rate the bank offers, and how often the bank compounds the interest—meaning how often it calculates interest on your interest. A $5,000 balance at 4.5% annual percentage yield (APY) will earn roughly $225 per year if interest compounds daily. The same balance at 0.01% APY earns about 50 cents per year. The difference between those two accounts is real money, and it comes down to which bank you choose and what type of account you open.

Key Takeaways

  • Interest rate and APY are not the same thing—APY includes the effect of compounding, so it is the number that tells you what you will actually earn.
  • High-yield savings accounts at online banks typically pay 4% to 5% APY, while traditional brick-and-mortar banks often pay under 0.5% on the same balance.
  • Interest compounds on a schedule the bank sets (usually daily or monthly), meaning you earn interest on your interest once it is deposited.
  • Moving money between accounts does not reset your interest—the bank calculates based on your balance on specific dates, not on how long you have held the account.

The difference between interest rate and APY

Banks advertise two numbers, and they are not interchangeable. The interest rate is the percentage the bank applies to your balance. The APY (annual percentage yield) is the rate you will actually earn over a year, including the effect of compounding.

If a bank offers 4.5% interest compounded daily, the APY will be slightly higher than 4.5%—usually around 4.59%—because you earn interest on the interest that gets added to your account each day. Over a year, that compounding effect adds up. A bank that compounds monthly will show a lower APY than one that compounds daily, even if the stated interest rate is identical. When you are comparing accounts, always look at the APY number, not the interest rate, because APY is what you will actually receive.

How compounding frequency affects your earnings

Compounding is the schedule on which the bank calculates interest and adds it to your account. The more often it compounds, the more you earn, because each time interest is added, the next calculation includes that new balance.

Imagine a $10,000 balance at 4% annual interest. If the bank compounds once per year, you earn $400 and end the year with $10,400. If it compounds daily (365 times per year), you earn roughly $408.33 because each day the bank calculates interest on a slightly larger balance. The difference grows with time and larger balances. Most online savings accounts compound daily. Many traditional banks compound monthly or quarterly. The bank's disclosure documents will state the compounding frequency—look for the phrase "compounded daily" or "compounded monthly" in the account terms.

Why online banks typically offer higher rates

Online banks have lower overhead costs than branches with physical locations, staff, and real estate. They pass some of that savings to customers in the form of higher interest rates. A typical online bank might offer 4.5% APY on a savings account, while a traditional bank with branches offers 0.15% on the same type of account. The money is equally safe at both (both are FDIC-insured up to $250,000), but the online bank's rate is roughly 30 times higher.

This is not a temporary promotion. The rate difference has persisted for years because the business models are fundamentally different. If you keep your savings at a traditional bank primarily for branch access or because you have a checking account there, you are trading higher interest earnings for convenience. That trade-off is yours to make, but it is worth knowing the cost. On a $50,000 balance, the difference between 0.15% and 4.5% is about $2,175 per year in foregone interest.

How banks calculate and deposit your interest

The bank uses your account balance on specific dates to calculate interest. Most banks use the average daily balance method: they add up your balance at the end of each day during the month, divide by the number of days, and explore the interest rate to that average. Some use the daily balance method, calculating interest each day on that day's balance. A few use the minimum balance method, explore the rate only to your lowest balance during the period. The account terms will specify which method the bank uses.

Interest is typically deposited monthly, though some accounts deposit it daily or quarterly. When it lands in your account, it becomes part of your balance and earns interest itself in the next compounding period. You do not have to do anything to receive it—the bank handles the calculation and deposit automatically. If you withdraw money mid-month, the bank recalculates based on the balance that was actually in the account, so withdrawals reduce the interest you earn that period.

How to find the highest rates available

Interest rates change constantly. Banks raise and lower their rates based on what the Federal Reserve does and what competitors are offering. A rate that is competitive today may not be in three months. To find current rates, visit the websites of online banks directly—Ally, Marcus, American Express Personal Savings, and Discover are common examples, but there are dozens. Compare the APY (not the interest rate), the compounding frequency, and any account minimums or restrictions.

Some accounts require a minimum balance to earn the advertised rate, or they charge a monthly fee if your balance drops below a threshold. Read the full account terms before opening. Websites like Bankrate and DepositAccounts track rates across banks and update them regularly, so you can see which banks are currently offering the highest APY without visiting each site individually. Once you open an account, your rate may change—banks can lower rates at any time, though they typically give notice before doing so.

Moving money between accounts and how it affects interest

Transferring money from one savings account to another does not reset your interest or cause you to lose earnings. The bank calculates interest based on the balance in each account on the dates it uses for calculation, regardless of when you moved the money or how many times you have moved it. If you transfer $5,000 from Bank A to Bank B on the 15th of the month, Bank A will calculate interest on the lower balance for the rest of the month, and Bank B will calculate interest on the higher balance starting from when the transfer clears.

The transfer itself takes one to three business days to clear, depending on the banks involved. During that time, the money is in transit and typically earns no interest. Once it lands in the receiving account, it begins earning interest on that bank's schedule. If you are moving money to take advantage of a higher rate, the interest you gain from the higher rate will quickly outweigh any interest you miss during the transfer period, especially if you are moving a substantial balance.

Frequently Asked Questions

Do I have to do anything to earn interest on my savings account?

No. Once you open the account and deposit money, the bank automatically calculates and deposits interest on the schedule stated in the account terms. You do not need to take any action. Interest will be added whether you check your balance or not.

What happens to my interest if I withdraw money before the month ends?

The bank recalculates interest based on the balance that was actually in the account. If you withdraw $2,000 mid-month, your interest for that month will be lower because the calculation uses the average or daily balance, which is now lower. You do not lose interest you have already earned, but you earn less interest going forward on the smaller balance.

Can a bank lower my interest rate after I open the account?

Yes. Banks can change rates at any time, though they typically provide notice before lowering a rate. If your rate drops and you find a better rate elsewhere, you can move your money to a different bank. There is no penalty for switching savings accounts.

Is my interest earnings taxable?

Yes. Interest earned in a savings account is taxable income. The bank will send you a 1099-INT form at the end of the year if you earned $10 or more in interest. You report this on your tax return. This is separate from the interest rate the bank pays you—it is about how the IRS treats the money you earn.

Why do some accounts offer different rates for different balance tiers?

Some banks offer higher APY on balances above a certain threshold—for example, 4.5% on balances over $25,000 and 3.5% on smaller balances. This is a way for banks to attract larger deposits. If you have a smaller balance, you will earn the lower rate. If you reach the threshold, your rate increases on the entire balance.