The interest you earn depends on your bank's rate and how much money you keep in the account

The amount of interest a savings account pays you is not fixed across all banks — it changes based on the rate your specific bank offers and the balance you maintain. A bank offering 4.50% annual percentage yield (APY) on a $5,000 balance will pay you roughly $225 per year in interest, while a bank offering 0.01% APY on the same balance pays about 50 cents. The difference between these two scenarios is real money, and it comes down to which bank you choose.

Interest accrues in two ways: straightforward interest (calculated once on your original balance) or compound interest (calculated on your balance plus previously earned interest). Most savings accounts use daily compounding, meaning the bank calculates interest every single day and adds it to your account. This compounds your earnings — you earn interest on your interest — though the effect is small with typical savings balances.

Key Takeaways

  • The interest you earn equals your account balance multiplied by the APY rate, divided by 365 days — so a $10,000 balance at 4.00% APY earns roughly $400 per year.
  • Online banks typically offer higher rates than brick-and-mortar banks because they have lower operating costs, though you cannot deposit cash in person.
  • Your interest rate can change at any time because banks adjust rates based on Federal Reserve decisions and market conditions.
  • Interest compounds daily at most banks, meaning you earn small amounts of interest on the interest you have already earned.
  • The interest you earn is taxable income, and your bank will send you a 1099-INT form if you earn $10 or more in a year.

How to calculate the interest you will earn

The basic formula is straightforward: multiply your balance by the APY, then divide by 365. If you have $5,000 in an account paying 4.50% APY, the math is $5,000 × 0.045 ÷ 365 = $0.62 per day. Over a full year, that adds up to roughly $225.

This calculation assumes your balance stays the same all year. In reality, most people deposit and withdraw money throughout the year, so your actual interest will vary. Banks calculate interest based on your daily balance, so deposits increase your daily interest earned and withdrawals decrease it. If you deposit an extra $2,000 midway through the year, your interest for the second half will be higher than the first half.

Compound interest makes the real number slightly higher than this straightforward calculation. When the bank adds your daily interest to your account, you earn interest on that interest the next day. With savings account rates, this effect is small — the difference between $225 and $226 on a $5,000 balance — but it grows larger with bigger balances or higher rates.

Why rates vary so much between banks

Online banks consistently offer higher rates than traditional banks with physical branches. A bank like Ally or Marcus might offer 4.50% APY while a major national bank offers 0.01% on the same type of account. The difference is not about one bank being generous — it is about cost. Online banks have no branch buildings to maintain, no tellers to pay, and lower overhead overall. They pass those savings to customers through higher interest rates.

Banks also set rates based on what the Federal Reserve does. When the Fed raises its benchmark interest rate, banks raise savings rates. When the Fed cuts rates, banks cut savings rates. This happens with a lag — sometimes weeks or months — so you might see your rate drop even if the Fed has not moved recently. The bank is responding to where they expect rates to go, not just where they are today.

Competition matters too. When many banks offer similar high rates, it is because they are competing for deposits. When rates are low across the board, it usually means the Fed has kept rates low and banks see no reason to offer more.

What happens to your rate over time

Your interest rate is not permanent. Banks can change the rate they pay on savings accounts at any time, and they do — sometimes weekly. You will not lose money if your rate drops; the interest you have already earned stays in your account. But future interest will be calculated at the new, lower rate.

Some banks notify you by email or through your online banking portal when rates change. Others do not. The safest approach is to check your account terms or log into your online banking dashboard every few months to see what rate you are currently earning. If your rate has dropped significantly and other banks are offering more, moving your money is straightforward — you can open a new account at a higher-rate bank and transfer your balance in a few days.

How interest compounds daily

Daily compounding means the bank calculates your interest each day and adds it to your account when ready. The next day, the bank calculates interest on your new, slightly higher balance — including the interest you just earned. This creates a compounding effect where your money grows a tiny bit faster than straightforward interest would suggest.

The math is small enough that it does not change your decision-making. On a $5,000 balance at 4.50% APY, daily compounding adds roughly $1 to your annual earnings compared to straightforward interest. On a $50,000 balance, it adds roughly $10. The real money comes from choosing a bank with a higher rate, not from the compounding method.

Interest is taxable income

The interest your savings account earns counts as income for tax purposes. If you earn $10 or more in interest during a calendar year, your bank will send you a Form 1099-INT by January 31 of the following year. You report this amount on your tax return, and you owe income tax on it at your regular tax rate.

This is one reason why high-yield savings accounts matter more than they used to. When rates were near zero, the tax burden was negligible. Now that rates are higher, the interest you earn is real money — and real tax liability. If you earn $400 in interest and you are in the 22% tax bracket, you owe roughly $88 in federal income tax on that interest. Choosing a bank with a higher rate means more interest to report, but also more money in your pocket after taxes.

Comparing rates across different banks

The easiest way to see current rates is to visit bank websites directly or use a rate comparison site. Bankrate, DepositAccounts, and NerdWallet all list savings rates from multiple banks updated daily. When you compare, look at the APY number — that is the rate that matters, because it already accounts for compounding.

Pay attention to account minimums and fees. Some banks require a minimum balance to earn the advertised rate, or they charge monthly fees that eat into your interest. A bank offering 4.50% APY with a $25,000 minimum is not the same deal as a bank offering 4.40% APY with no minimum. Read the fine print before you open an account.

Also check whether the bank is FDIC-insured. This means your deposits are protected up to $250,000 if the bank fails. All legitimate banks are FDIC-insured, but it is worth confirming, especially with smaller online banks you may not have heard of.

Frequently Asked Questions

How often does interest get added to my account?

Interest is calculated daily but usually added to your account monthly. Some banks add it more frequently. Check your account statement or online banking dashboard to see when deposits appear. The timing does not affect your total annual interest — you earn the same amount whether it is added daily, monthly, or quarterly.

If I withdraw money mid-month, do I lose all the interest I earned that month?

No. Interest is calculated on your daily balance, so you earn interest for each day the money was in the account. If you have $5,000 for 15 days and $3,000 for 15 days, you earn interest on both amounts for the days they were there. You do not lose interest for the days you held the money.

Can a bank lower my interest rate without telling me?

Yes. Banks can change rates at any time without notifying you in advance. Some banks email you when rates change, but many do not. You should check your rate periodically by logging into your account or calling the bank. If your rate drops significantly, you can move your money to a higher-rate bank.

Why do some savings accounts pay almost nothing?

Banks with physical branches have higher costs and often pay lower rates. They may also assume customers will not shop around. Online banks and credit unions typically offer higher rates because they have lower overhead. If your current bank pays 0.01% APY, moving to a bank paying 4.50% APY would earn you roughly $225 per year on a $5,000 balance instead of 50 cents.

Is the interest I earn the same every month?

No, because it depends on your daily balance. Months with higher balances earn more interest. Also, if your bank changes its rate during the month, your interest for that month will be split between the old rate and the new rate based on the days each rate was in effect.