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 through mortgages, car loans, and business lines of credit. The bank keeps the difference between what it pays you and what it charges borrowers. That payment to you is called interest.

The bank calculates your interest based on three things: how much money you have in the account, how long it stays there, and the interest rate the bank offers. The interest rate is a percentage — typically between 0.01% and 5.35% per year, depending on the account type and the bank. The higher the rate, the more money you earn.

Interest gets added to your account automatically on a schedule set by the bank — usually daily, monthly, or quarterly. Once interest is deposited, it becomes part of your balance and earns interest itself the next time the bank calculates. This is called compound interest, and it means your money grows faster over time.

Key Takeaways

  • Banks pay you interest as a percentage of your balance in exchange for holding your money and lending it to other customers.
  • The interest rate varies by bank and account type, and higher rates mean more money earned on the same balance.
  • Interest compounds — meaning you earn interest on your interest — which accelerates growth the longer money stays in the account.
  • The frequency of compounding (daily, monthly, or quarterly) affects how much total interest you receive over a year.
  • Savings accounts are FDIC-insured up to $250,000, so your principal and earned interest are protected even if the bank fails.

How the interest rate is set and what it means for your money

Banks set their own interest rates based on what the Federal Reserve charges them to borrow money. When the Fed raises its rate, banks eventually raise the rates they offer on savings accounts. When the Fed lowers its rate, savings account rates typically fall too. This is why the rate you see today may be different from the rate you saw six months ago.

The rate advertised by a bank is called the Annual Percentage Yield (APY). This is the total interest you would earn in one year if you made no deposits or withdrawals and the rate stayed constant. A bank offering 4.50% APY means that on a $10,000 balance held for a full year with no activity, you would earn $450 in interest (before any fees).

Different account types within the same bank often have different rates. High-yield savings accounts typically offer rates 10 to 20 times higher than traditional savings accounts at the same bank. Money market accounts and certificates of deposit (CDs) may offer even higher rates, but they come with restrictions on how often you can withdraw money.

How compounding multiplies your interest over time

Compounding is the process where interest earned gets added to your balance, and then that larger balance earns interest in the next period. The more frequently interest compounds, the more you earn.

Here is a concrete example: suppose you deposit $5,000 in an account with a 4% APY that compounds monthly. After one month, the bank calculates 4% ÷ 12 months = 0.33% of your $5,000, which is about $16.67. Your new balance is $5,016.67. The next month, the bank calculates 0.33% of $5,016.67, which is about $16.72. You earned $0.05 more because you earned interest on the previous month's interest. Over a full year, that compounding effect adds up to about $204 in total interest instead of $200.

The longer money stays in the account untouched, the more compounding works in your favor. After 10 years at 4% APY compounded monthly, that same $5,000 grows to about $7,459. After 20 years, it reaches about $11,140. The difference between 10 and 20 years is $3,681 — more than the original deposit — all from compounding.

What happens when you make deposits or withdrawals

Every time you deposit money, that new amount starts earning interest when ready (or on the next compounding date, depending on the bank). Every time you withdraw money, the interest calculation for the next period is based on the lower balance.

Some accounts have limits on how many withdrawals you can make per month without a fee. Federal rules previously capped savings account withdrawals at six per month, but that rule was suspended in 2020 and has not been reinstated. However, individual banks may still enforce their own withdrawal limits, so check your account agreement. Exceeding the limit typically costs $10 to $35 per extra withdrawal.

If you withdraw money before interest is credited, you do not lose the interest you have already earned — it stays in your account. But you do lose the interest that would have been calculated on the withdrawn amount in future periods.

The difference between stated rate and actual earnings

The APY you see advertised is the rate assuming your balance stays constant and you make no withdrawals. In real life, most people deposit and withdraw money throughout the year, which changes how much interest they actually earn.

Some banks use a method called average daily balance to calculate interest. 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. This means a large withdrawal late in the month reduces your average balance for that entire month, even if you deposit the money back a few days later.

Other banks use the daily balance method, which calculates interest on your actual balance each day. This is generally more favorable to you because you earn interest on money the moment it enters the account, rather than waiting for a monthly average.

Fees and conditions that reduce your interest earnings

Even with a high interest rate, certain fees can eat into your earnings. Monthly maintenance fees (typically $5 to $15) are charged by some banks if your balance falls below a minimum or if you do not meet other conditions. Overdraft fees, excess withdrawal fees, and inactivity fees all reduce your net interest earnings.

Some accounts require a minimum balance to earn the advertised rate. If your balance drops below that threshold, the bank may pay a much lower rate on the entire balance. For example, a bank might offer 4.50% APY on balances of $25,000 or more, but only 0.01% on smaller balances.

Read the account agreement or call the bank to confirm whether there are fees, minimum balance requirements, or conditions attached to the advertised rate. A high rate with a $25,000 minimum and a $10 monthly fee may earn you less than a lower rate with no minimums or fees.

How to compare interest rates across banks

Interest rates change frequently, so the rate you see today may not be available next week. When comparing accounts, look at the current APY, not the rate from a month ago. Most banks display the APY prominently on their website and in account disclosures.

Use a rate comparison tool or visit several banks' websites directly to see current rates. Online banks typically offer higher rates than brick-and-mortar banks because they have lower overhead costs. Credit unions sometimes offer competitive rates to their members, though you must be a member to open an account.

Consider the total package, not just the rate. An account with a 4.75% APY but a $25,000 minimum balance and a $10 monthly fee may not be better than an account with a 4.50% APY, no minimum, and no fees — especially if you cannot maintain the higher balance consistently.

Frequently Asked Questions

Can I lose money in a savings account?

No. Your principal (the money you deposit) is protected by FDIC insurance up to $250,000 per account holder per bank. Interest earned is also covered by this insurance. The only way your balance decreases is if you withdraw money or if fees exceed the interest you earn.

Is the interest rate may provide to stay the same?

No. Banks can change the interest rate on savings accounts at any time without notice. Rates typically move in the same direction as Federal Reserve rate changes, but the timing and amount vary by bank. Check your account statements or log into your online banking to see if your rate has changed.

What is the difference between APY and APR?

APY (Annual Percentage Yield) includes the effect of compounding and shows what you actually earn. APR (Annual Percentage Rate) does not include compounding and is used for loans and credit cards. For savings accounts, always look at the APY, not the APR.

Do I have to pay taxes on interest I earn?

Yes. Interest earned on savings accounts is taxable income. Banks send you a 1099-INT form each January showing how much interest you earned the previous year. You report this on your federal tax return. The amount is usually small unless your balance is very large or the interest rate is unusually high.

How often should I move my money to get the best rate?

You do not need to move money frequently. Once you find an account with a competitive rate and no fees, leaving the money there allows compounding to work. If rates rise significantly and stay high for several months, it may be worth moving to a higher-rate account, but the effort and time cost usually outweigh the benefit of chasing small rate increases.