How Banks Make Money
Learn how banks earn from the gap between what they pay savers and charge borrowers.
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Why how banks make money matters
Understanding how banks make money explains why savings rates at big banks are so low, why online banks can offer 4–5% APY, and why borrowing is expensive. This knowledge helps you make better decisions about where to keep your money and where not to borrow.
The core model: interest rate spread
Banks make most of their money through a simple mechanism:
- You deposit $1,000 in your savings account. The bank pays you 1% interest ($10/year).
- The bank lends that $1,000 to another customer at 7% interest ($70/year).
- The bank earns $70, pays you $10, and keeps $60.
The difference between the rate paid to depositors and the rate charged to borrowers is called the interest rate spread, and it's the bank's primary revenue source. On billions of dollars in deposits, that 6% spread generates enormous profit.
Your deposit funds someone else's loan
When you deposit money in a bank, it doesn't sit in a vault with your name on it. Banks are required to keep a percentage as reserves, but they lend out the rest. Your $1,000 deposit might become part of a $200,000 mortgage for someone else. That mortgage pays the bank 7%. The bank pays you 1%. The 6% difference is profit, and it's why banks want your deposits.
Why online banks pay more
Traditional banks (Chase, Bank of America) have thousands of physical branches, ATMs, and staff. These cost enormous amounts of money to maintain. Online banks (Ally, Marcus, SoFi) have no branches, their entire operation runs through software. Lower overhead means they can afford to pay depositors more and still make a profit.
Typical rates:
- Major traditional bank savings account: 0.01%–0.1% APY
- Online high-yield savings account: 4%–5% APY
On $1,000, that's $0.10 vs $45. Both are FDIC insured. The only difference is whether you need physical branch access.
What changes the outcome
Banks also make money through fees (overdraft fees, ATM fees, monthly account fees), credit card interchange fees (the merchant pays a percentage each time a card is swiped), and investment banking services. The interest rate spread is the biggest, but fees are why banks fight hard to sign up new checking account customers.
Compound interest
Final amount: $2,159
Interest earned: $1,159
How to think it through
The bank's incentive is not aligned with yours on savings rates. A big bank earns roughly the same money whether it pays you 0.01% or 4.5% on savings, it's lending at 7% either way. So it pays you as little as competition allows. This is why you need to actively compare savings rates rather than accepting whatever your bank offers by default.
Similarly, the bank's incentive is to keep you borrowing for as long as possible (minimum payments on credit cards, long loan terms). Understanding this makes you a more skeptical consumer of banking products.
Real-world example
Marcus has $3,000 in a traditional bank savings account earning 0.01% APY. After a year, she has $3,000.30. A friend tells her about a high-yield savings account at an online bank paying 4.5% APY. She switches. After one year, she has $3,135. She earned $134.70 more just by moving her money. After five years at 4.5% (compounding), she has $3,732. The traditional bank would have given her $3,001.50. The bank's product hasn't changed, she just chose the one that pays more.
You deposit $1,000 in a savings account paying 1%. The bank lends that money to a borrower at 7%.
How does this arrangement affect you as the depositor?
Practice the idea
The practical application of understanding how banks make money is this: always compare savings rates before opening an account, and always compare loan rates before borrowing. A high savings rate puts more of the spread in your pocket. A low loan rate reduces how much the bank earns at your expense.
Which choice best shows understanding of how banks make money?
A student faces your deposit funding someone else's loan. What is the smartest first step?
A bank pays 1% interest on savings accounts and charges 7% interest on personal loans. What is the bank's interest rate spread, and why does it matter?
You deposit $1,000 in a savings account. The bank lends most of that money to another customer as a personal loan. How does this arrangement benefit you as the depositor?
Bring it into your life
Go to a rate comparison site or Google "high-yield savings account APY" and compare what your current bank pays vs what online banks pay. If you're earning under 1% on savings, you're leaving significant money on the table annually. Opening a high-yield savings account at an online bank takes 10 minutes and can earn you 40× more interest on the same deposit.
Banks profit from the interest rate spread: they pay depositors ~1% and lend money at ~7%, keeping the ~6% difference. Your deposit is lent to other customers, you earn a small return, the bank earns a larger one. Online banks offer higher savings rates because they have lower overhead. Always compare rates before opening a savings account or taking a loan.