What you earn depends on the bank, the account type, and the current rate environment

The amount of interest you earn in a savings account is determined by three things: the annual percentage yield (APY) the bank offers, how much money you keep in the account, and how long you leave it there. A bank offering 4.5% APY on $10,000 will pay you roughly $450 per year, but a bank offering 0.01% APY on the same amount will pay you about $1. The difference between these two scenarios is real and measurable — it's the reason shopping around for rates matters.

Interest rates change constantly. Banks raise and lower their APY based on what the Federal Reserve does with its benchmark rate, how much competition exists in your area, and whether the bank is trying to attract new deposits. A rate that is competitive today may not be in three months. The only way to know what you'll actually earn is to check the current rate at the specific bank where you keep your money, then do the math yourself.

Key Takeaways

  • Your earnings equal the APY multiplied by your balance, divided by 365 days — so $10,000 at 4.5% APY earns about $450 per year, or $1.23 per day.
  • Online banks typically offer higher APY than brick-and-mortar banks because they have lower overhead costs, though the difference varies month to month.
  • High-yield savings accounts (HYSA) are not a product category with a fixed definition — they are simply savings accounts with higher-than-average APY, and that rate can change at any time.
  • Interest compounds daily at most banks, meaning you earn interest on the interest you've already earned, but the effect is small unless your balance is large or the rate is high.
  • Money market accounts and certificates of deposit (CDs) may offer higher rates than savings accounts, but they come with restrictions on how often you can withdraw.

How the math works: calculating your annual interest

The formula is straightforward: multiply your account balance by the APY, then divide by 365. If you have $25,000 in a savings account with a 4.0% APY, you earn $25,000 × 0.04 ÷ 365 = $2.74 per day, or about $1,000 per year. Most banks calculate and deposit interest monthly, so you would see roughly $83 added to your account each month.

This assumes your balance stays the same all year. If you add money or withdraw money, the interest calculation changes for that period. A bank that compounds interest daily (which most do) recalculates what you've earned every single day based on your current balance, so deposits and withdrawals shift your earnings immediately.

The difference between simple interest and compound interest is usually small in a savings account. Compound interest means you earn interest on the interest you've already earned. At 4.0% APY on $25,000, the difference between simple and compound interest over one year is about $4 — not nothing, but not life-changing. The effect grows larger with bigger balances or higher rates, but for most people in a savings account, the difference is negligible.

Why rates vary so much between banks

Online banks almost always offer higher APY than traditional banks with physical branches. An online bank has no tellers, no rent on a building, and no staff in a lobby — those savings get passed to depositors as higher interest rates. A brick-and-mortar bank in your town might offer 0.01% APY while an online bank offers 4.5% APY on the exact same type of account. Both are real rates, both are current, and both are available to you if you're willing to move your money.

Banks also adjust rates based on competition and the Federal Reserve's actions. When the Fed raises its benchmark rate, banks typically raise savings account APY within weeks or months. When the Fed cuts rates, banks cut savings account APY much faster — sometimes within days. This asymmetry means your rate can drop suddenly, but it rises slowly.

Some banks use APY as a marketing tool to attract new customers, offering a high introductory rate for a few months, then dropping it. Always check the current rate before you move money, and check it again every few months to see if you're still earning a competitive rate at your current bank.

Savings accounts versus money market accounts and CDs

A money market account is a hybrid between a savings account and a checking account. It typically offers higher APY than a regular savings account, but it comes with a limit on how many times you can withdraw per month (usually six). If you need to access your money frequently, the higher rate may not be worth the restriction.

A certificate of deposit (CD) locks your money away for a set period — three months, six months, one year, five years, or longer. In exchange, the bank offers a higher APY than you'd get in a savings account. If you withdraw before the term ends, you pay a penalty, which is usually a certain number of months' worth of interest. A CD makes sense only if you know you won't need the money for the full term and you want to lock in a rate before rates fall.

The tradeoff is simple: the longer you agree to lock up your money, the higher the rate. A one-year CD might pay 4.5% APY, while a five-year CD might pay 5.0% APY. But if you withdraw from the five-year CD after two years, you lose several months of interest as a penalty, which can wipe out the benefit of the higher rate.

How interest is taxed

Interest you earn in a savings account is taxable income. The bank will send you a Form 1099-INT at the end of the year if you earned $10 or more in interest (the threshold varies slightly by bank). You report this amount on your tax return as ordinary income, and you pay tax on it at your regular income tax rate.

This matters because it reduces your real earnings. If you earn $1,000 in interest and you're in the 24% federal tax bracket, you owe $240 in federal taxes on that interest. Your actual take-home is $760. Some states also tax interest income, so your real earnings could be even lower. When comparing accounts, remember that the APY is the gross rate — your net earnings after taxes will be less.

When interest rates are rising versus falling

If the Federal Reserve is raising rates, your savings account APY will eventually rise too, but usually with a lag. Banks are slow to raise savings rates because they want to keep the spread between what they pay depositors and what they charge borrowers as wide as possible. If you're in a rising-rate environment, you may want to wait a few months before locking money into a CD, because rates will likely go higher.

If the Federal Reserve is cutting rates, your savings account APY will fall quickly. Banks cut deposit rates fast because they want to protect their profit margins. If you think rates are about to fall, a CD can lock in today's rate for the full term. But if rates are already falling, you're probably too late — the best rates were available a few months ago.

Frequently Asked Questions

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

Yes, if you move from a low-rate bank to a high-rate bank. But the benefit only applies to new deposits or the balance you move. If you've been earning 0.01% APY on $50,000 and you move to a bank offering 4.5% APY, you gain roughly $2,200 per year in additional interest. The downside is the time and hassle of opening a new account and transferring money, plus the risk of missing a deposit or payment during the transition.

What happens to my interest if the bank lowers its APY?

The interest you've already earned stays in your account. Only future interest is calculated at the new, lower rate. If your bank drops the APY from 4.5% to 2.0%, the money you've already earned at 4.5% doesn't change — but starting the next day, new interest accrues at 2.0%. This is why checking your rate every few months matters: if your bank cuts rates and competitors are offering more, moving your money makes financial sense.

Is a high-yield savings account safe?

Yes, as long as the bank is FDIC-insured. FDIC insurance protects up to $250,000 per depositor per bank, so your money is safe even if the bank fails. Online banks are FDIC-insured just like brick-and-mortar banks. The higher APY is not a sign of risk — it's simply the result of lower operating costs.

How often is interest added to my account?

Most banks calculate interest daily but deposit it monthly. Some deposit quarterly or annually. Check your account agreement to see the schedule. The frequency doesn't change your annual earnings — whether interest is deposited monthly or annually, you earn the same total amount over the year (assuming the rate stays the same).

Should I put all my money in a CD if rates are high?

Only if you won't need the money for the full CD term. If you lock $50,000 into a five-year CD at 5.0% APY and you need the money after two years, you'll pay a penalty that could erase years of interest gains. Keep enough in a regular savings account for emergencies, and only put money into a CD if you're certain you can leave it untouched.