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

When you put money in a savings account, the bank lends that money to other customers as mortgages, car loans, and business loans. The bank charges those borrowers interest—a percentage of what they borrowed. The bank keeps most of that interest, but shares a portion with you as payment for letting them use your money. That payment is your savings account interest.

The amount you earn depends on three things: how much money you have in the account, what interest rate the bank offers, and how long the money sits there. A higher balance, a higher rate, or more time all mean more interest paid to you.

Key Takeaways

  • Banks pay you interest on savings account deposits because they lend your money to other customers and keep the difference between what they pay you and what they charge borrowers.
  • Your interest earnings depend on your account balance, the bank's interest rate, and how long your money stays in the account.
  • Interest compounds, meaning you earn interest on your interest, which is why leaving money untouched for longer periods grows your balance faster.
  • Banks can change their interest rates at any time, so the rate you see today may be different next month.
  • The actual dollars you earn from interest vary widely depending on the bank and account type—some accounts earn nearly nothing while others earn significantly more.

How the bank calculates what it owes you

Banks use a formula based on your balance, the interest rate, and the time period. The most common method is called daily compounding. Each day, the bank calculates interest on your current balance and adds it to your account. The next day, it calculates interest on the new, slightly larger balance—including the interest from yesterday.

Here is a concrete example. Say you have $1,000 in an account earning 4.5% annual interest, compounded daily. On day one, the bank calculates one day's worth of interest (4.5% divided by 365 days, then multiplied by $1,000). That comes to roughly $0.12. Your balance is now $1,000.12. On day two, the bank calculates interest on $1,000.12, not the original $1,000. This is called compounding, and it is why your money grows faster the longer it sits.

After one year at 4.5% compounded daily, your $1,000 becomes roughly $1,046—not exactly $1,045, because of the compounding effect. The difference seems small with $1,000, but with larger balances or higher rates, compounding makes a real difference.

Why the interest rate changes

Banks set their own interest rates based on what the Federal Reserve does. The Federal Reserve is the central bank of the United States, and it sets a target range for the interest rate that banks charge each other for overnight loans. When the Fed raises that rate, banks typically raise the rates they offer on savings accounts. When the Fed lowers it, banks usually lower savings rates too.

Banks also compete with each other. If one bank offers 4.5% and another offers 3.5%, customers move their money to the higher rate. This competition pushes rates up. When fewer people are opening savings accounts or when banks have plenty of deposits, they may lower their rates because they do not need to attract as much new money.

Your bank can change your interest rate at any time, with or without notice. Some banks notify customers before a rate change; others do not. This means the rate you earn today may be different in a month. If your rate drops and you want a higher one, you can move your money to a different bank.

The difference between APY and interest rate

Banks advertise two slightly different numbers: the interest rate and the APY (Annual Percentage Yield). The interest rate is the percentage the bank pays. The APY includes the effect of compounding over one year.

If a bank offers 4.5% interest compounded daily, the APY will be slightly higher—perhaps 4.60%—because of compounding. The APY is the number that matters for comparing accounts, because it shows you the actual return you will receive in one year if you do not withdraw any money.

When you are shopping for a savings account, always compare the APY, not the interest rate. Two banks might advertise the same interest rate but offer different APYs depending on how often they compound (daily, monthly, or quarterly).

How often interest is added to your account

Even though banks calculate interest daily, they do not add it to your account every day. Most banks credit (deposit) the interest into your account monthly. Some do it quarterly. A few do it daily, though this is rare.

The timing does not change how much you earn—daily compounding still happens behind the scenes—but it does affect when you see the money in your account. If your bank credits interest monthly, you will see a deposit on the same day each month. If it credits quarterly, you will see deposits four times a year.

You can find out how often your bank credits interest by reading your account agreement or calling customer service. The agreement will also tell you whether the bank compounds daily, monthly, or quarterly.

What happens to interest when you withdraw money

If you withdraw money before the interest is credited, you lose the interest that would have been earned on that amount. For example, if you have $5,000 and withdraw $2,000 on the 15th of the month, the bank calculates interest only on the remaining $3,000 for the rest of the month.

Some savings accounts have withdrawal limits or withdrawal fees if you take money out too often. Federal rules used to require this, but those rules changed. Now it depends on your bank and account type. Check your account agreement to see whether your account has limits or fees.

If you need the money soon, a savings account is still the right place for it because you can withdraw anytime without penalty (unless your specific account has a fee). The interest you earn, even if modest, is better than keeping cash in a checking account or under your mattress.

How to find an account with a higher interest rate

Interest rates vary significantly between banks. A traditional bank branch might offer 0.01% APY on savings, while an online bank might offer 4.5% or higher. The difference comes down to overhead costs—online banks have fewer physical locations and lower expenses, so they can afford to pay depositors more.

To find a higher rate, search for "high-yield savings accounts" or check comparison websites that list current rates from multiple banks. Read the fine print to understand any requirements: some accounts require a minimum balance, charge monthly fees if your balance drops below a threshold, or limit how many times you can withdraw per month.

Moving your money to a higher-rate account takes a few days but is straightforward. You open a new account at the new bank, transfer your money (the new bank can often do this for you), and close the old account once the transfer is complete. You do not lose any interest you have already earned.

Frequently Asked Questions

Do I have to pay taxes on savings account interest?

Yes. Interest earned on a savings account is taxable income. At the end of the year, your bank sends you a Form 1099-INT showing how much interest you earned. You report this on your tax return. The amount of tax you owe depends on your total income and tax bracket.

Why do some savings accounts earn almost no interest?

Traditional banks often offer very low rates (0.01% to 0.05%) because they have high costs—paying employees, maintaining branches, and advertising. Online banks and credit unions often offer higher rates because they have lower overhead. Shop around rather than assuming all banks offer the same rate.

Can I lose money in a savings account?

No. Your deposits are protected by the FDIC (Federal Deposit Insurance Corporation) up to $250,000 per account holder per bank. You cannot lose your principal, though inflation can reduce what your money can buy. Interest earnings are separate from this protection.

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

Money market accounts often offer higher interest rates than savings accounts, but they may require a larger minimum balance and limit how many times you can withdraw per month. Both are FDIC-insured. Choose based on whether you need frequent access to your money.

If I move my money to a different bank, do I lose the interest I already earned?

No. Interest that has already been credited to your account is yours to keep. You only lose future interest if you withdraw before it is credited. When you transfer to a new bank, you take all your money plus all interest earned with you.