Banks lend out the money you deposit and keep the difference between what they pay you and what borrowers pay them

A savings account makes money for the bank, not for you—though you do earn interest. Here is how it works: you deposit $5,000. The bank pays you 4.5% annual interest, which is about $225 per year. But the bank turns around and lends that same $5,000 to someone else at 8% interest, earning $400 per year. The bank keeps the $175 difference. That gap—between the rate paid to depositors and the rate charged to borrowers—is called the interest rate spread, and it is the core of how banks make money.

Your money does not sit in a vault. Banks are required to keep only a small percentage on hand (the reserve requirement, which varies but is often around 10% for certain account types). The rest gets deployed when ready: lent to mortgage borrowers, car buyers, credit card holders, and businesses. The bank is betting that enough borrowers will repay on time to cover what they owe you plus their operating costs and profit.

The interest rate you receive is not set by how much the bank earns on your money specifically. It is set by the federal funds rate—the rate the Federal Reserve charges banks to borrow from each other overnight. When that rate is high, banks pay depositors more to attract money. When it is low, they pay less. Your bank's rate also depends on competition in your area, the type of account, and how much you deposit.

Key Takeaways

  • Banks earn money by lending out deposits at higher interest rates than they pay you, keeping the difference as profit.
  • Your deposit is not held in reserve; it is lent to other customers within hours or days of being deposited.
  • The interest rate you earn is tied to the federal funds rate and market competition, not to what your specific money earns when lent out.
  • Banks also earn fees on overdrafts, monthly maintenance, and other account services, which is a second source of profit separate from interest spread.
  • The FDIC insures your deposits up to $250,000 per account type per bank, so the bank's lending risk does not fall on you.

The federal funds rate sets the floor for what banks pay you

The Federal Reserve does not set savings account interest rates directly. Instead, it sets the federal funds rate—the interest rate at which banks lend reserve balances to each other overnight. This rate influences everything else. When the Fed raises its rate, banks have to pay more to borrow from each other, so they raise the rates they pay depositors to keep money flowing in. When the Fed cuts its rate, banks lower deposit rates because they can borrow more cheaply.

Your bank's actual rate will be lower than the federal funds rate. A typical pattern: the Fed's rate is 5.25% to 5.50%, and a high-yield savings account might pay 4.5% to 5.0%. The difference reflects the bank's cost of operations, risk, and profit margin. Banks in competitive markets (where many banks offer savings accounts) tend to pay higher rates. Banks in less competitive areas can pay less and still retain deposits.

The rate you see advertised is also called the Annual Percentage Yield (APY). This includes the effect of compounding—interest earned on interest. A 4.5% APY means that if you deposit $10,000 and add nothing else, you will have $10,450 after one year (assuming monthly compounding, the actual amount will be slightly higher due to how compounding works).

Banks manage risk by holding reserves and spreading lending across many borrowers

If a bank lent out every dollar it received, it would collapse the moment depositors wanted their money back. Banks are required by law to hold a minimum percentage of deposits in reserve—money that cannot be lent out. The exact percentage depends on the size of the bank and the type of account, but it is typically 10% for transaction accounts and 0% for savings accounts (though banks hold reserves anyway as a safety practice).

Beyond reserves, banks manage risk by diversifying their lending. A bank with $100 million in deposits does not lend it all to one borrower. It spreads loans across thousands of mortgages, auto loans, credit cards, and business lines. If one borrower defaults, the loss is absorbed across the entire portfolio. The bank prices each loan to account for expected defaults—a riskier borrower pays a higher rate to compensate.

The FDIC (Federal Deposit Insurance Corporation) insures your deposits up to $250,000 per account type per bank. This means if the bank fails and cannot repay you, the FDIC steps in. This insurance does not come from your account; it is funded by banks themselves through insurance premiums. It protects you from the bank's lending failures, so you do not bear the risk of bad loans.

Interest rate spreads vary by account type and economic conditions

Not all savings accounts have the same spread. A money market account might pay 4.8% while a regular savings account at the same bank pays 3.5%. The difference reflects how the bank expects to use the money. Money market accounts often have higher minimum balances and withdrawal restrictions, which means the bank can lend that money out for longer periods at higher rates. A regular savings account has no restrictions, so the bank cannot count on having the money for long—it might be withdrawn tomorrow—so it pays less.

Spreads also widen and narrow with economic conditions. During a recession, banks become more cautious about lending and may lower rates to borrowers while keeping deposit rates high to attract safety-conscious savers. During a boom, banks compete fiercely for deposits and raise rates. The spread can range from 1% to 4% or more depending on the economy and the bank's strategy.

Online banks typically offer higher savings rates than brick-and-mortar banks because they have lower operating costs—no branches, no tellers, no physical real estate. They can afford a smaller spread and still be profitable. A traditional bank might pay 0.5% while an online bank pays 4.5% on the same type of account, even though both are lending out your money at similar rates to borrowers.

Banks also earn money through fees, not just interest spread

Interest spread is the largest source of bank profit, but not the only one. Banks charge overdraft fees when you spend more than your balance—typically $25 to $35 per overdraft. They charge monthly maintenance fees on some accounts, ATM fees if you use another bank's machine, and wire transfer fees. Some accounts waive these fees if you maintain a minimum balance or set up direct deposit.

These fees are separate from interest spread and represent pure profit—the bank is not lending anything out. A bank with 100,000 customers paying $10 per month in fees earns $12 million per year from fees alone, before counting a single dollar of interest spread. This is why banks push for overdraft protection and why they make it straightforward to accidentally trigger fees.

What happens to your money after you deposit it

The timeline is fast. You deposit $5,000 on a Monday morning. By Monday afternoon, the bank has recorded the deposit in your account and begun the process of clearing the funds (verifying the money actually came from your employer or the other bank). By Tuesday or Wednesday, the funds are cleared and available to you. Within hours of clearing, the bank has already lent portions of that money out—some to a mortgage borrower, some to a credit card holder, some to a small business.

Your account balance reflects your claim on the bank, not a specific pile of bills. The bank does not set aside your $5,000 in a separate envelope. Instead, your $5,000 is pooled with millions of other deposits, and the bank tracks what it owes you. When you withdraw $500, the bank reduces what it owes you by $500 and hands you cash (or transfers it electronically). The bank covers this withdrawal from its reserve, from new deposits coming in, or by calling in a loan early if necessary.

This system works because most people do not withdraw all their money at once. Banks count on steady deposits flowing in to cover steady withdrawals flowing out. A bank run—when many depositors try to withdraw at the same time—can force a bank to sell loans at a loss or fail entirely. This is rare in the modern era because of FDIC insurance and Federal Reserve lending facilities, but it is the reason banks care deeply about maintaining confidence.

Frequently Asked Questions

Why do savings account rates change so often?

Rates change because the Federal Reserve adjusts the federal funds rate in response to inflation and economic conditions. Banks pass these changes to depositors within days or weeks. A rate that is 4.5% one month might be 4.75% the next if the Fed raises rates, or 4.25% if the Fed cuts. Banks also adjust rates based on how much deposit money they need—if they have excess deposits, they lower rates; if they need more, they raise them.

Can a bank fail and take my money with it?

No, because of FDIC insurance. If your bank fails, the FDIC pays you up to $250,000 per account type. The insurance is funded by banks, not by you. The last major bank failure in the United States was in 2023, and all insured deposits were paid in full. Your money is safer in a bank account than in cash under a mattress.

Do I earn interest on the interest I earn?

Yes, if your account compounds interest. Most savings accounts compound monthly or daily. If you earn $10 in interest one month, the next month you earn interest on that $10 plus your original balance. Over a year, this compounds to slightly more than the stated APY. The more frequently interest compounds, the more you earn.

Why do some banks pay almost no interest on savings?

Banks that pay very low rates (0.01% or less) are betting that customers will not shop around or do not know better. These are usually large traditional banks with extensive branch networks. They can afford to pay less because they have brand recognition and convenience. Online banks and credit unions, which have lower costs, typically pay much higher rates and compete on rate alone.

What is the difference between a savings account and a money market account in terms of how the bank uses the money?

The bank uses both the same way—lending the money out to borrowers. The difference is in restrictions. A money market account usually requires a higher minimum balance and limits withdrawals, so the bank can count on having the money longer and lends it out at higher rates. A savings account has no restrictions, so the bank cannot count on the money staying, and it lends more conservatively or keeps more in reserve.