The amount you earn depends on the interest rate, how much you deposit, and how long the money sits there

Your savings account interest is calculated by multiplying your account balance by the annual percentage yield (APY) the bank offers, then dividing by the number of days in a year. If you keep $10,000 in an account paying 4.5% APY for a full year without adding or withdrawing money, you'll earn roughly $450. But most people deposit and withdraw throughout the year, so your actual earnings will be lower—the bank only pays interest on the money that's actually there each day.

The real number that matters is the APY, not the interest rate. APY includes the effect of compounding—the way interest gets added to your balance and then earns interest itself. Banks are required to show you the APY prominently when you open an account, so you can compare one bank against another fairly.

Interest rates change constantly. The Federal Reserve sets a target range that influences what banks pay, and that range has moved several times in recent years. When you see a rate advertised online, it's the rate that bank is offering right now—not a promise of what you'll earn forever. Some banks lower their rates within weeks of advertising them.

Key Takeaways

  • Your earnings equal your average daily balance multiplied by the APY, divided by 365 days—so a $5,000 balance at 4% APY earns about $200 per year.
  • APY is the only number you need to compare between banks, because it already includes compounding.
  • Interest rates change frequently, so the rate you see advertised today may be lower next month.
  • Money market accounts and certificates of deposit sometimes pay higher rates than regular savings accounts, but with different rules about when you can withdraw.

How banks calculate what you earn each day

Most banks use a method called "daily balance" compounding. Each day, they calculate interest on the exact balance in your account at the end of that day. That daily interest gets added to your account, usually once a month. The next day, you earn interest on the new, slightly larger balance—that's compounding.

Here's a concrete example: if you have $10,000 at 4.5% APY, the bank divides 4.5% by 365 days to get a daily rate of about 0.0123%. On day one, you earn $1.23. That gets added to your balance, so on day two you have $10,001.23 and earn interest on that amount. By the end of a year, you've earned $460 instead of exactly $450, because of compounding.

If you add money during the month, the new deposit starts earning interest immediately at the daily rate. If you withdraw money, you stop earning interest on that amount. This is why the timing of deposits and withdrawals matters—money that sits in the account longer earns more.

Why different account types pay different rates

A regular savings account typically pays the lowest rate. A money market account usually pays more, but requires a higher opening deposit (often $2,500 or more) and may limit how many withdrawals you can make per month. A certificate of deposit (CD) pays the highest rate, but you agree to leave your money there for a set time—three months, one year, five years—and you pay a penalty if you withdraw early.

Banks pay more for money market accounts and CDs because they know the money will stay put longer. With a regular savings account, you might withdraw your balance tomorrow, so the bank can't count on having that money to lend out. With a CD, the bank knows exactly how long it has your money, so it can lend it out with confidence and pay you more.

Online banks typically pay higher rates than brick-and-mortar banks across all account types, because they have lower overhead costs. A regular savings account at an online bank might pay 4% to 5%, while the same account at a traditional bank might pay 0.01% to 0.5%.

What happens to your interest if rates drop

If you have a regular savings account or money market account, the rate can change at any time. The bank can lower it without your permission, and many banks have done exactly that as interest rates have fallen. You'll see the new rate reflected in your next monthly statement, and interest will be calculated at the lower rate going forward.

If you have a CD, your rate is locked in for the entire term. If you open a one-year CD at 5% APY, you'll earn 5% for that full year, even if the bank's advertised rate drops to 3% next month. This is the main advantage of a CD—you know exactly what you'll earn.

The tradeoff is that if rates rise, you're stuck with your lower rate unless you withdraw the money early and pay the penalty. Most CDs charge a penalty equal to a few months of interest—so if you withdraw from a one-year CD after six months, you might lose three months' worth of interest.

How to estimate your earnings before you open an account

Use this simple formula: take your deposit amount, multiply it by the APY shown, and divide by 100. That gives you your annual earnings if the money sits untouched for a full year.

Example: $5,000 deposit × 4.5% APY ÷ 100 = $225 per year, or about $18.75 per month.

If you plan to add money regularly, the math gets more complicated, but you can estimate by using your average balance instead of your opening deposit. If you start with $5,000 and add $500 per month, your average balance over the year is roughly $8,000. Using $8,000 in the formula gives you a rough idea of what you'll earn.

Remember that this is an estimate. Your actual earnings will vary depending on exactly when you deposit and withdraw money, and whether the bank changes its rate during the year.

The difference between APY and APR

You may see both APY and APR mentioned. APY (annual percentage yield) is what you earn on savings. APR (annual percentage rate) is what you pay on borrowed money, like a credit card or loan. They're calculated differently because one is money coming to you and one is money going out. Always use APY when comparing savings accounts.

Some banks advertise a base interest rate and then separately show the APY. The APY is the number that matters for your actual earnings, because it includes compounding. The base rate alone will understate what you actually earn.

Why your earnings might be lower than you expect

The most common reason is that you didn't keep the full balance in the account for the full year. If you opened an account with $10,000 at 4.5% APY but withdrew $5,000 after six months, you didn't earn $450. You earned roughly $225 on the first $10,000 for six months, plus roughly $112 on the remaining $5,000 for six months, totaling about $337.

Another reason is that the bank changed its rate. If you opened an account at 4.5% but the bank lowered it to 3% after three months, your annual earnings would be lower than if the rate had stayed at 4.5% all year.

A third reason is fees. Some savings accounts charge monthly maintenance fees, which come directly out of your balance and reduce your earnings. High-yield savings accounts rarely charge fees, but it's worth checking before you open an account.

Frequently Asked Questions

How often does the bank add interest to my account?

Most banks add interest monthly, though some add it daily or quarterly. You'll see the interest posted to your account on a specific day each month, usually the last day or the first day. Check your account agreement to see the exact schedule for your bank.

Can I lose money in a savings account?

No. The interest rate can go down, so you earn less, but your principal balance is protected. If your bank fails, the FDIC insures up to $250,000 per account type per bank, so you won't lose your deposit.

Is the interest I earn taxable?

Yes. Interest earned in a savings account is considered income and is taxable. Your bank will send you a 1099-INT form at the end of the year if you earned $10 or more in interest, and you'll report that on your tax return. The amount varies by state and federal tax brackets.

What's the highest interest rate I can find right now?

Rates change constantly and vary by bank. Online banks typically offer the highest rates on savings accounts, usually in the 4% to 5% range, though this changes frequently. Check current rates on banking comparison websites to see what's available today.

Should I move my money to a higher-paying account?

If your current account pays significantly less than what's available elsewhere—more than 1% lower—it may be worth moving. Calculate how much extra you'd earn in a year at the higher rate. If it's more than the effort to switch, consider moving. Keep in mind that rates can change, so today's best rate may not be the best rate next month.