What determines how much interest you earn

The amount of interest your savings account earns depends on three things: the annual percentage yield (APY) the bank offers, how much money you keep in the account, and how long it stays there. A bank offering 4.5% APY on a $10,000 balance will pay you roughly $450 per year—but that exact number shifts if you add money, withdraw it, or the bank changes its rate.

Banks set their own APY rates based on what the Federal Reserve charges them to borrow money. When the Fed raises its benchmark rate, banks typically raise savings APYs within weeks or months. When the Fed cuts rates, banks lower savings APYs much faster—sometimes within days. This means the rate you see today may not be the rate you earn six months from now.

The bank compounds your interest, usually daily or monthly. Compounding means you earn interest on your interest. With daily compounding at 4.5% APY, a $10,000 deposit grows slightly faster than straightforward math suggests, because each day's tiny interest payment starts earning its own interest the next day.

Key Takeaways

  • Your earnings depend on the APY rate, your account balance, and how long the money stays deposited—not on how often you check your balance.
  • Banks change savings APY rates frequently, so the rate you lock in today may drop in three months or rise if the Fed raises rates again.
  • High-yield savings accounts at online banks typically pay 4% to 5% APY, while traditional brick-and-mortar banks often pay under 0.5% APY on the same deposit.
  • Interest compounds daily at most banks, meaning you earn small returns on your returns, but the difference between daily and monthly compounding is usually less than $10 per year on a $10,000 balance.
  • You pay income tax on all interest earned, so your actual take-home return is lower than the APY—the exact amount depends on your tax bracket.

How to calculate what you'll actually earn

The simplest way to estimate your earnings is to multiply your balance by the APY and divide by 12 for a monthly estimate. A $25,000 balance at 4.5% APY earns roughly $93.75 per month before taxes. This math assumes your balance stays flat and the rate doesn't change.

If you want a more precise number, most banks show your year-to-date interest earned in your online account dashboard. This is the actual amount the bank has already credited to your account, accounting for the exact days your money sat there and the exact compounding schedule they use. You can also use a savings calculator—enter your balance, the APY, and how many months you plan to keep the money, and it will show you the projected total.

Remember that the interest you earn is taxable income. If you earn $500 in interest over a year and you're in the 22% federal tax bracket, you'll owe roughly $110 in federal income tax on that interest. Some states also tax savings interest. Your bank will send you a 1099-INT form in January if you earned $10 or more in interest during the previous year.

Why savings rates vary so much between banks

Online banks pay higher APY than traditional banks because they have lower overhead costs—no branch buildings, fewer employees, no ATM networks to maintain. An online bank can pass those savings to customers in the form of higher interest rates. A brick-and-mortar bank with 500 branches nationwide has to cover those costs somehow, and lower savings rates are how they do it.

Some banks also use savings rates as a loss leader to attract new customers, knowing they'll cross-sell checking accounts, credit cards, or loans later. These promotional rates sometimes drop after a few months, so read the fine print before moving your money.

Banks also compete differently depending on the market. During periods when the Fed is raising rates, online banks often raise their savings APYs faster than traditional banks to grab deposits. During periods when the Fed is cutting rates, all banks lower their rates, but online banks sometimes hold their rates higher longer to keep customers from leaving.

How long it takes to see interest in your account

Most banks credit interest monthly, on the last day of the month or the first day of the next month. Some credit it daily, but you won't see the money move until the end of the month when they post all the daily accruals at once. A few banks credit quarterly or even annually, though this is rare for savings accounts.

The interest appears as a deposit in your account—you don't have to do anything to receive it. Once it's credited, it becomes part of your balance and starts earning interest itself the next day. If you withdraw money before the interest posts, you don't lose the interest you've already earned; you only lose the interest you would have earned on the money you withdrew.

What happens when the Fed changes rates

When the Federal Reserve raises its benchmark rate, banks usually raise savings APYs within one to four weeks. Online banks tend to move faster than traditional banks. When the Fed cuts rates, banks lower savings APYs much faster—sometimes within days—because they're eager to reduce what they pay depositors.

This creates an asymmetry: your rate shoots up slowly when rates are rising, but drops quickly when rates are falling. If you lock in 4.5% APY today and the Fed cuts rates next month, your bank may drop your rate to 3.5% within weeks. But if the Fed raises rates next month, your bank may take six weeks to raise your rate to 5%.

You don't have to accept a rate cut. If your bank lowers your APY and you don't like the new rate, you can move your money to a different bank offering a higher rate. There's no penalty for closing a savings account and moving your balance elsewhere.

Comparing savings accounts across different banks

The easiest way to compare is to look at the APY each bank advertises, then check whether that rate applies to all balances or only balances above a certain threshold. Some banks offer 4.5% APY on balances up to $100,000, then 3.5% APY on anything above that. Others offer the same rate on all balances.

Also check the minimum balance required to open the account and whether the bank charges monthly fees. A savings account with a $25 monthly fee and 4.5% APY is worse than one with no fee and 4.3% APY, because the fee eats into your earnings. Most online banks have no minimum balance and no monthly fees.

Finally, confirm that the bank is FDIC-insured. This means your deposits up to $250,000 are protected by federal insurance if the bank fails. All major banks are FDIC-insured, but it's worth checking if you're using a smaller or newer bank.

The difference between savings accounts and money market accounts

Money market accounts and savings accounts earn interest the same way—the bank pays you an APY based on your balance. The main differences are that money market accounts often require a higher minimum balance (sometimes $2,500 or more), may limit how many withdrawals you can make per month, and sometimes offer slightly higher APY to compensate for those restrictions.

For most people, a high-yield savings account is simpler. You can withdraw money whenever you want without penalty, there's usually no minimum balance, and the APY is competitive with money market accounts. Money market accounts make sense only if you have a large balance and don't need frequent access to the money.

Frequently Asked Questions

Can I earn more interest by moving my money between banks?

Yes, if you move your money from a bank paying 0.5% APY to one paying 4.5% APY, you'll earn nine times as much interest on the same balance. However, moving money takes a few days, and you'll miss a few days of interest at the old rate. The lost interest is usually less than $5 on a $10,000 balance, so it's worth moving if the new rate is significantly higher.

What if my bank lowers my APY after I deposit money?

Banks can change APY rates at any time without notice, and the change applies to your existing balance when ready. You have no obligation to stay—you can move your money to a different bank offering a higher rate. There's no penalty for closing a savings account.

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

Yes, all interest earned is taxable income. If you earn $10 or more in a calendar year, your bank sends you a 1099-INT form in January. You report this on your tax return. If you earn less than $10, you still owe tax on it, but the bank doesn't send a form.

Is a high-yield savings account safe?

Yes, as long as the bank is FDIC-insured. Your deposits up to $250,000 are protected by federal insurance if the bank fails. All major online banks offering high-yield savings accounts are FDIC-insured. You can verify this on the FDIC website.

How often should I check my savings account APY?

Check it every few months, especially if the Fed has recently changed rates. If your bank's APY has dropped significantly below what other banks are offering, moving your money takes 5 to 10 minutes and can earn you hundreds of dollars per year on a large balance.