What you earn depends on the rate, your balance, and how long the money sits there

The amount of interest you make in a savings account is the product of three things: the annual percentage yield (APY) the bank offers, how much money you have in the account, and how long it stays there. A $10,000 balance at 4.5% APY earns roughly $450 per year if the rate stays constant. A $1,000 balance at the same rate earns roughly $45. The math is straightforward, but the real variables—what rate you can actually get, whether that rate changes, and how banks calculate daily interest—are where the picture gets complicated.

Banks calculate interest in different ways. Most savings accounts use daily compounding, which means they calculate what you owe interest on each day, then add that interest back into your balance so the next day's calculation includes it. This compounds your earnings over time, but the effect is modest in savings accounts. A $10,000 balance earning 4.5% APY with daily compounding earns about $450 per year whether you think of it as straightforward or compound interest—the difference is a few dollars. Where compounding matters more is in longer time horizons or higher balances, and in accounts that compound monthly or quarterly instead of daily.

Key Takeaways

  • Your interest earnings equal the APY rate multiplied by your account balance, so doubling your balance doubles your earnings at the same rate.
  • Most savings accounts compound interest daily, meaning interest gets added to your balance and earns interest itself, though the effect is small in typical accounts.
  • The APY you see advertised is only may provide for new money if the bank says so—rates change, and your rate may drop after an introductory period.
  • High-yield savings accounts at online banks currently offer rates between 4% and 5.35%, while traditional brick-and-mortar banks often offer under 0.5%.
  • Interest is taxable income, and you will receive a 1099-INT form from your bank if you earn $10 or more in a year.

How the math works with real numbers

If you keep $5,000 in a savings account earning 4.5% APY for one full year without adding or withdrawing money, you earn $225 in interest. That $225 is calculated as $5,000 × 0.045 = $225. If you keep the same $5,000 there for six months, you earn roughly $112.50. If you withdraw $2,500 halfway through the year, your earnings drop because the second half of the year is calculated on $2,500 instead of $5,000.

The daily compounding piece works like this: the bank divides the annual rate by 365 (or sometimes 360, depending on the bank), then applies that daily rate to your balance each day. With a 4.5% APY, the daily rate is roughly 0.0123%. On a $5,000 balance, that's about $0.62 per day. The next day, if the interest was added, the calculation is on $5,000.62, not $5,000. Over a year, this compounding adds a few extra dollars compared to straightforward interest, but not dramatically. The real benefit of daily compounding shows up over decades or with much larger balances.

Why the rate you see advertised may not be the rate you get

Banks advertise rates that are current as of the moment you see them, but rates change. The Federal Reserve sets a target range for short-term interest rates, and banks adjust their savings account rates in response. When the Fed raises rates, banks raise savings rates. When the Fed cuts rates, banks cut savings rates—sometimes quickly, sometimes slowly. A rate advertised as 4.5% today might be 3.8% in three months if the Fed cuts rates and your bank follows.

Some banks offer an introductory rate for new customers, which expires after a set period (often three to six months). After the introductory period ends, your rate drops to the bank's standard rate, which may be much lower. Always read the fine print to see whether the advertised rate is permanent or temporary. If you are comparing accounts, compare the standard ongoing rate, not the promotional rate, unless you plan to move your money before the promotion ends.

High-yield savings accounts versus traditional bank accounts

The difference in earnings between account types is dramatic. A traditional bank might offer 0.01% to 0.5% APY on savings. A high-yield savings account at an online bank typically offers between 4% and 5.35% APY as of early 2025. On a $10,000 balance, the traditional account earns $1 to $50 per year. The high-yield account earns $400 to $535 per year. That gap widens with larger balances and longer time horizons.

High-yield accounts are offered by online banks and some credit unions because they have lower overhead costs than brick-and-mortar branches. They pass those savings to customers in the form of higher rates. The tradeoff is that you cannot walk into a physical location to deposit cash or speak to someone in person. Most high-yield accounts allow transfers from external banks, which takes one to three business days. If you need when ready access to cash, a high-yield account works fine for money you are not touching regularly. For an emergency fund or money you plan to keep for months or years, the higher rate makes a real difference in your earnings.

How taxes affect what you actually keep

Interest earned in a savings account is taxable income. If you earn $10 or more in interest during a calendar year, your bank sends you a 1099-INT form by January 31 of the following year. You report this income on your tax return, and you owe federal income tax on it at your ordinary income tax rate. Some states also tax interest income.

This means your actual take-home earnings are less than the interest amount. If you earn $450 in interest and your tax rate is 22%, you owe roughly $99 in federal tax, leaving you with $351. The exact amount depends on your total income and tax bracket. For people in higher tax brackets, the tax bite is larger. This does not change the math of which account to choose—a high-yield account still beats a traditional account after taxes—but it is worth factoring in when you are calculating expected earnings.

What happens to your interest if rates drop

If you have money in a savings account and the Federal Reserve cuts interest rates, your bank will eventually cut the rate on your account. How quickly depends on the bank. Some cut rates within days of a Fed cut. Others wait weeks or months. There is no rule requiring them to match the Fed's move when ready, and different banks move at different speeds.

This is one reason to shop around periodically. If your bank's rate drops to 2% and another bank is offering 4.5%, moving your money costs nothing except the time to set up a transfer. Your existing balance does not get locked in at the old rate—the rate you earn going forward is whatever the bank is currently paying. If you want to protect yourself against rate drops, some banks offer rate-lock promotions where they may provide a rate for a set period, but these are uncommon and usually only explore to new deposits.

Money market accounts and certificates of deposit as alternatives

Savings accounts are not the only place to earn interest on cash. Money market accounts typically offer rates similar to high-yield savings accounts but may require a higher minimum balance and allow you to write checks or make debit card purchases. Certificates of deposit (CDs) lock your money away for a set term—three months, six months, one year, five years—in exchange for a may provide rate that is usually higher than a savings account rate. If you withdraw money from a CD before the term ends, you pay a penalty, usually a few months' worth of interest.

CDs make sense if you know you will not need the money for a specific period and want to lock in a rate before rates drop. Savings accounts make sense if you might need the money sooner or want flexibility. Money market accounts sit in the middle—higher rates than savings, but with some restrictions on how often you can withdraw.

Frequently Asked Questions

How often is interest added to my savings account?

Most banks calculate interest daily but add it to your account monthly. Some add it quarterly or annually. Check your account agreement or ask your bank. The frequency does not change your annual earnings much, but daily calculation means you earn interest on interest more often than if the bank calculated monthly.

Can I lose money in a savings account?

No. Your principal is protected by FDIC insurance up to $250,000 per account holder per bank. Interest rates can drop, so your earnings may be lower than you expected, but your balance will not go down unless you withdraw money. The only exception is if you withdraw from a CD early and pay a penalty larger than the interest earned.

Is the interest rate may provide to stay the same?

No. Banks can change rates at any time unless they specifically promise otherwise in writing. Introductory rates expire. Rates drop when the Fed cuts rates. If you want a may provide rate, a CD locks in a rate for the term length, but you cannot access the money without paying a penalty.

What if I add money to my account during the year?

Interest is calculated on your balance each day, so adding money increases your earnings going forward. If you deposit $5,000 on January 1 and another $5,000 on July 1, the first $5,000 earns interest for the full year, and the second $5,000 earns interest for six months. Your total earnings are higher than if you had kept only $5,000 the whole time.

Do I have to report savings account interest on my taxes?

Yes, if you earn $10 or more in a year. Your bank sends you a 1099-INT form, and you report the interest as income on your tax return. You owe federal income tax on it at your ordinary rate. Some states tax interest income as well. Keep your 1099-INT with your tax records.