Interest is money the bank pays you for keeping your money there

When you deposit money into a savings account, the bank lends that money to other customers through mortgages, car loans, and credit cards. In exchange for the use of your money, the bank pays you interest—a percentage of your balance, calculated and added to your account on a schedule the bank sets. The more money you keep in the account and the higher the interest rate, the more you earn.

The bank publishes an annual percentage rate (APR), which tells you what percentage of your balance you'll earn in a year if the rate stays the same. A savings account with a 4.5% APR means that if you keep $1,000 in the account for a full year without withdrawing or depositing anything, you'll earn $45 in interest. That $45 gets added to your account, so your new balance becomes $1,045.

Interest rates vary widely between banks and change over time. Online banks typically offer higher rates than brick-and-mortar banks because they have lower overhead costs. Rates also move up and down based on what the Federal Reserve does with its benchmark interest rate—when the Fed raises rates, banks usually raise savings account rates too, and vice versa.

Key Takeaways

  • Banks pay you interest on savings account balances as compensation for letting them use your money.
  • The annual percentage rate (APR) tells you what percentage of your balance you'll earn in one year, though the actual amount depends on how long your money stays in the account.
  • Interest compounds, meaning you earn interest on your interest, which makes your balance grow faster over time.
  • Online banks usually offer higher interest rates than traditional banks, but rates change frequently and vary by institution.
  • The Federal Reserve's interest rate decisions influence what banks offer on savings accounts.

How compounding multiplies your interest over time

Compounding is when the bank calculates interest on your balance plus any interest you've already earned. This creates a snowball effect where your money grows faster the longer it sits in the account.

Here's a concrete example: You deposit $5,000 in a savings account with a 4% APR. After one month, the bank calculates interest on $5,000 and adds about $16.67 to your account (one-twelfth of 4% of $5,000). Your new balance is $5,016.67. The next month, the bank calculates interest on $5,016.67, not the original $5,000, and adds about $16.72. Over a year, that compounding adds up to roughly $204 in total interest, not the $200 you'd earn if interest were calculated only once.

Banks compound interest on different schedules: daily, weekly, monthly, or quarterly. Daily compounding grows your money faster than monthly compounding because interest gets added more often. When comparing two savings accounts with similar APRs, check how often each one compounds—daily is better than monthly.

The difference between APR and APY

Banks use two different numbers to describe interest rates, and they mean different things. APR (annual percentage rate) is the interest rate without accounting for compounding. APY (annual percentage yield) includes the effect of compounding.

If a savings account has a 4% APR with daily compounding, the APY will be slightly higher—usually around 4.08% depending on the exact compounding schedule. Over a year, that small difference compounds into real money. A $10,000 deposit earning 4% APR with daily compounding will grow to about $10,408 (the 4.08% APY effect), not $10,400.

When you're comparing savings accounts, always look at the APY, not the APR. The APY tells you the true amount you'll earn. Banks are required to display both numbers, but the APY is what actually matters for your decision.

What happens to your interest if you withdraw money

Interest is calculated based on your balance during the period when interest is added. If you withdraw money before the interest is posted, you lose the interest you would have earned on that withdrawn amount.

For example: You have $5,000 in an account earning 4% APY. On the 25th of the month, the bank calculates interest on your $5,000 balance and will add about $16.67 on the 1st of next month. But if you withdraw $2,000 on the 28th, the bank still calculates interest based on the $5,000 you had during most of the month, so you still get the full $16.67. However, if you withdraw $2,000 on the 1st before interest posts, you lose the interest you would have earned on that $2,000.

Some savings accounts have minimum balance requirements—if your balance drops below a certain amount, the bank may stop paying interest or charge you a monthly fee. Check your account terms to see if yours has this rule.

How interest rates change and what affects them

Savings account interest rates are not fixed. Banks change their rates based on what the Federal Reserve does with its benchmark interest rate, which it adjusts several times a year. When the Fed raises its rate, banks usually raise savings rates within days or weeks. When the Fed cuts its rate, banks often cut savings rates too, though sometimes more slowly.

The current economic environment also matters. During periods of high inflation, the Fed raises rates to cool down spending, and savings rates go up. During recessions, the Fed lowers rates to encourage borrowing and spending, and savings rates fall. If you lock in a high rate today, that rate may drop in a few months if the Fed cuts rates.

Different banks move at different speeds. Online banks often raise rates faster than traditional banks when the Fed moves, and they may cut rates more slowly too. If you're earning a good rate, monitor it over time—if it drops significantly, you can move your money to a bank offering a better rate without penalty (savings accounts have no early withdrawal fees).

How to calculate interest on your own balance

You can estimate how much interest you'll earn using a simple formula. Multiply your balance by the APY, then divide by 12 for a monthly estimate, or divide by 365 for a daily estimate.

Monthly estimate: (Balance × APY) ÷ 12. If you have $10,000 at 4.5% APY, you'll earn roughly ($10,000 × 0.045) ÷ 12 = $37.50 per month.

Yearly estimate: Balance × APY. The same $10,000 at 4.5% APY earns roughly $10,000 × 0.045 = $450 per year.

These are estimates because actual interest depends on the exact compounding schedule and whether your balance changes. Your bank's website usually has an interest calculator you can use for a more precise number. Your monthly statement also shows exactly how much interest you earned that month.

Why some accounts earn more interest than others

Savings accounts at different banks offer different rates, and some account types within the same bank earn more than others. High-yield savings accounts typically offer rates 10 to 20 times higher than traditional savings accounts at big banks. A traditional bank might offer 0.01% APY while an online bank offers 4.5% APY on the same $10,000 deposit—that's a difference of $450 per year.

Online banks offer higher rates because they have lower costs: no physical branches, fewer employees, and lower overhead. They pass those savings to customers through better interest rates. Credit unions sometimes offer competitive rates too, especially if you're a member.

Money market accounts are another option. They typically offer rates similar to high-yield savings accounts but may require a higher minimum balance. Certificates of deposit (CDs) lock your money away for a set period (3 months to 5 years) and usually pay higher rates than savings accounts, but you can't withdraw without a penalty.

Frequently Asked Questions

Is the interest I earn on a savings account taxed?

Yes. Interest income is taxable as ordinary income at your federal tax rate. If you earned $100 in interest during the year, you report that $100 as income on your tax return. Your bank sends you a 1099-INT form in January if you earned $10 or more in interest during the previous year.

Can I lose money if interest rates drop?

No. Your account balance stays the same—you just earn less interest going forward. If you had $10,000 earning 4.5% APY and the rate drops to 2%, you still have $10,000, but you'll earn less each month. You can move your money to a different bank without penalty.

How often should I check my interest rate?

Check it every few months, especially if the Federal Reserve has announced rate changes. If your rate drops significantly below what other banks are offering, moving your money takes 5 to 10 business days and costs nothing. Many people set a calendar reminder to check rates quarterly.

What's the difference between a savings account and a money market account?

Money market accounts usually offer higher interest rates but require a larger minimum balance (often $2,500 or more) and may limit how many withdrawals you can make per month. Savings accounts are more flexible but typically pay less interest. Both are insured by the FDIC up to $250,000.