What you earn depends on the bank's rate, how much you deposit, and how long you leave it there
The amount of interest you earn 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 earn $450. If you deposit $10,000 for six months at 4.5% APY, you earn roughly $225. The math is straightforward, but the real variables—how long you keep the money there, whether you add to it, and which bank you choose—are what change your actual earnings.
Banks set their own rates, and those rates change. Right now, rates at online banks range from under 0.01% at some traditional brick-and-mortar banks to over 5% at certain online savings accounts and money market accounts. The difference between 0.01% and 5% on $10,000 is the difference between $1 and $500 per year. Where you bank matters more than most people realize.
Key Takeaways
- Your annual earnings equal your balance multiplied by the APY, so a $5,000 deposit at 4.5% APY earns $225 per year.
- Interest compounds daily at most banks, meaning you earn interest on your interest, but the effect is small on balances under $50,000.
- Online banks typically offer rates two to five times higher than traditional banks because they have lower overhead costs.
- Moving money between accounts stops the interest clock on the old account and restarts it on the new one, so timing matters if rates change.
- High-yield savings accounts and money market accounts earn the same way, but money market accounts may let you write checks or use a debit card.
How interest compounds and when you see the money
Most banks compound interest daily, which means they calculate what you owe you once per day and add it to your balance. That new balance then earns interest the next day. Over a year, daily compounding earns slightly more than annual compounding, but the difference is small. On $10,000 at 4.5% APY, daily compounding earns about $46 more than if interest were added once at year-end—not nothing, but not life-changing.
You typically see the interest hit your account once per month. Some banks deposit it on the first of the month, others on the last day of the month, and a few on a different schedule. The bank's website or account agreement will tell you when. The interest is yours to keep; if you withdraw it, your balance goes down, but you do not owe it back.
If your balance changes during the month—you deposit $2,000 or withdraw $1,500—the bank recalculates based on your average daily balance or your ending balance, depending on the account terms. Most savings accounts use average daily balance, which means deposits and withdrawals made mid-month affect your earnings proportionally.
Why online banks pay more than traditional banks
An online bank with no physical branches has lower costs than a bank with hundreds of locations, staff, and real estate. Those savings get passed to customers as higher interest rates. A traditional bank might pay 0.01% on savings while an online bank pays 4.75% on the same type of account. The money is equally safe at both—the Federal Deposit Insurance Corporation (FDIC) insures up to $250,000 per depositor per bank—but your earnings are vastly different.
This gap has narrowed slightly in recent years as traditional banks have raised their rates under pressure, but online banks still lead. If you have $25,000 in savings, the difference between 0.01% and 4.75% is $1,187 per year. That is real money, and it costs you nothing to move your account.
How to compare rates across banks
Banks publish their APY on their websites, usually on the savings account or money market account product page. The rate you see is the one you get; there is no negotiation or tiering based on how much you deposit, though some banks do offer slightly higher rates for larger balances. Read the fine print to confirm whether the rate is promotional (good for a limited time) or standard (ongoing).
Websites like Bankrate, DepositAccounts, and the FDIC's own rate comparison tool let you sort by APY and see what dozens of banks are currently offering. Rates change weekly or even daily, so a rate you see today may be different next week. If you find a bank offering a rate you like, open the account soon—but do not rush into a decision based on a single day's comparison.
When comparing, also check the minimum deposit required to open the account and whether there are monthly fees. Some banks require $25,000 to open a high-yield savings account; others require $0. A $10 monthly fee erases the benefit of a slightly higher rate on a small balance.
What happens to your earnings if rates drop
If you lock in a 4.75% rate today and the bank drops it to 3.5% next month, your existing balance continues earning 4.75% until the bank changes your rate. Banks can lower rates without your permission, and they usually do so by sending a notice 30 days in advance. You can then move your money to a different bank if you want, but you lose the higher rate on any new deposits.
The reverse is also true: if rates rise and your bank does not raise yours, you can move to a competitor. This is why checking your rate quarterly against what other banks are offering is worth doing. A difference of 1% on $50,000 is $500 per year—enough to justify an hour spent moving money.
Interest earned on money market accounts versus savings accounts
Money market accounts and high-yield savings accounts earn interest the same way: your balance times the APY, compounded daily, paid monthly. The difference is in what you can do with the money. A savings account is designed for storage; you can withdraw anytime, but you cannot write checks or use a debit card. A money market account often includes check-writing or a debit card, making it more like a checking account that also earns interest.
Money market accounts sometimes pay slightly higher rates than savings accounts at the same bank, but not always. Compare the specific products at the bank you are considering. The convenience of a debit card may be worth a slightly lower rate, or it may not—that depends on how often you need to access the money.
How taxes affect your interest earnings
Interest you earn is taxable income. If you earn $500 in interest during a calendar year, that $500 is added to your other income when you file taxes. The bank will send you a 1099-INT form in January showing how much interest you earned in the previous year. You report this on your tax return, and you pay income tax on it at your ordinary tax rate.
This means a 4.75% rate is not actually 4.75% after taxes if you are in a higher tax bracket. If you pay 24% in federal income tax, your real after-tax return is closer to 3.6%. This does not change how much interest the bank pays you, but it is worth understanding when you are deciding whether to keep money in savings or invest it elsewhere.
Frequently Asked Questions
Can I earn interest on money I deposit mid-month?
Yes. If you deposit $5,000 on the 15th of the month and the account pays 4.5% APY, you earn interest on that $5,000 starting immediately. Most banks calculate interest based on your average daily balance, so a mid-month deposit earns roughly half the monthly interest compared to money that was there the whole month.
What if I withdraw money before the month ends?
You lose interest on the amount you withdrew, but only for the days it was gone. If you had $10,000 earning 4.5% APY and withdrew $3,000 on the 20th of a 30-day month, you earn interest on $10,000 for 19 days and $7,000 for 11 days. The bank recalculates automatically.
Do I have to do anything to earn interest?
No. Interest accrues automatically once you open the account and deposit money. You do not need to opt in or take any action. The bank calculates and deposits it monthly without you doing anything.
Is the interest rate may provide to stay the same?
No. Banks can lower rates at any time with 30 days' notice. They can also raise rates without notice. Your rate is only may provide for as long as the bank chooses to offer it. If rates rise and your bank does not raise yours, you can move your money to a competitor.
What if the bank fails?
Your deposits and accrued interest are protected up to $250,000 per depositor per bank by the FDIC. If a bank fails, the FDIC pays you the full amount, including interest earned up to the date of failure. This protection applies to all FDIC-insured banks, whether online or traditional.