What determines how much interest your savings account earns

The amount of interest you earn depends on 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 bank offering 4.5% APY on $10,000 for one year will pay you roughly $450 in interest (before any fees reduce it). A different bank offering 0.01% APY on the same $10,000 will pay you about $1. The difference between those two outcomes is real money, and it comes down to which bank you choose.

Banks set their own APY rates based on what the Federal Reserve charges them to borrow money, how much competition exists in your area, and what type of account you open. Online banks typically offer higher rates than brick-and-mortar branches because they have lower overhead costs. Promotional rates—sometimes called "special" or "limited-time" rates—are higher for the first few months, then drop to a standard rate. Money market accounts and certificates of deposit (CDs) often pay more than regular savings accounts, but they come with restrictions on how often you can withdraw.

Key Takeaways

  • The interest you earn is calculated by multiplying your account balance by the APY, divided by 365 days, then compounded daily or monthly depending on the bank's terms.
  • APY rates vary widely between banks—from under 0.01% at some traditional banks to over 5% at online banks, so comparing before you open an account matters.
  • Promotional rates are real but temporary; they usually last three to twelve months before dropping to a lower standard rate.
  • Money market accounts and CDs pay higher interest than savings accounts but restrict how often you can withdraw without penalty.
  • Interest compounds, meaning you earn interest on your interest, but only if you leave the money untouched and the bank compounds daily rather than monthly.

How banks calculate the interest you receive

Banks use a formula: your daily balance multiplied by the APY, divided by 365, then compounded at intervals the bank chooses. If you have $5,000 in an account with 4.5% APY and the bank compounds daily, you earn roughly $0.62 per day. That daily interest gets added to your balance, and the next day you earn interest on the new total—that's compounding.

The timing matters. A bank that compounds daily will pay you slightly more than one that compounds monthly, even if both advertise the same APY. The difference is small on modest balances but grows as your balance grows. Most online banks compound daily. Some traditional banks compound monthly or quarterly, which means you earn less even at the same stated rate.

Your balance also fluctuates. If you deposit $10,000 on the first of the month and withdraw $5,000 on the fifteenth, the bank calculates interest on $10,000 for fifteen days and $5,000 for the remaining days. Some banks use the "average daily balance" method instead, which smooths out the ups and downs. Read the account terms to see which method your bank uses.

Why rates differ so much between banks

Online banks pay more because they don't maintain physical branches, don't employ as many staff, and don't spend money on advertising the way traditional banks do. That lower cost structure means they can pass higher rates to depositors. A Chase savings account might pay 0.01% APY while an online bank like Marcus or Ally pays 4.25% APY on the same $10,000—the difference is entirely about business model, not about the safety of your money.

Credit unions sometimes offer competitive rates to their members, though you have to be a member to open an account. Banks also raise and lower rates based on what the Federal Reserve does. When the Fed raises its benchmark rate, banks gradually increase what they pay on savings. When the Fed cuts rates, banks cut what they pay—sometimes quickly, sometimes slowly.

Promotional rates are a temporary boost. A bank might advertise 5.35% APY for the first three months, then drop to 4.25% after that. The promotional rate is real—you do earn that higher rate during the promotional period—but plan for the rate to fall. Read the fine print to see when the promotion ends and what the standard rate will be.

How much interest you earn on different account types

A regular savings account at a traditional bank might pay 0.01% to 0.05% APY. On $10,000, that's $1 to $5 per year. The same $10,000 in an online savings account at 4.5% APY earns $450 per year. That gap widens the longer you leave the money untouched and the larger your balance grows.

Money market accounts typically pay 0.5% to 1% more than regular savings accounts at the same bank, but they limit how many withdrawals you can make per month (usually six). CDs lock your money away for a set term—three months, one year, five years—and pay higher rates in exchange. A one-year CD might pay 5.25% APY while a savings account at the same bank pays 4.5%. The tradeoff is that you cannot touch the money without paying an early withdrawal penalty, usually equal to a few months of interest.

High-yield savings accounts are regular savings accounts with higher APY rates. They are not a separate product category—they are just savings accounts at banks that choose to pay more. The term "high-yield" is marketing language, not a legal definition. Any savings account paying above 4% APY is usually called high-yield, but that threshold changes as rates move.

What happens to your interest if you withdraw money early

Withdrawing from a savings account does not trigger a penalty—you can take your money out whenever you want. But you lose the interest you would have earned on that money going forward. If you withdraw $5,000 from a $10,000 balance mid-month, you only earn interest on the remaining $5,000 for the rest of the month. The interest you already earned stays in your account.

CDs are different. If you withdraw before the maturity date, the bank charges an early withdrawal penalty. That penalty is usually three to six months of interest. A $10,000 CD paying 5% APY with a six-month penalty means you lose roughly $250 if you withdraw early. The bank deducts the penalty from your principal, so you get back less than you deposited.

Money market accounts fall in between. You can withdraw without penalty, but the account limits how many withdrawals you can make per month. If you exceed the limit, the bank may charge a fee per excess withdrawal or convert your account to a regular savings account with a lower rate.

How inflation affects what your interest actually buys

Interest is only useful if it outpaces inflation. If your savings account pays 1% APY but inflation is running at 3%, your money is losing purchasing power even though the balance is growing. A dollar in your account today buys less next year if inflation is higher than your interest rate.

When inflation is high, the interest rates banks offer tend to rise too, because the Federal Reserve raises its benchmark rate. When inflation is low, rates fall. Right now, savings account rates are higher than they have been in years because inflation was high and the Fed responded by raising rates. That may not last. Rates move based on Federal Reserve decisions, not on what is "fair" or what you need.

This is why comparing rates matters most when rates are changing. If you lock money into a CD at 5.5% APY and rates fall to 2%, you are glad you locked in. If rates rise to 6.5% and your CD is stuck at 5.5%, you lose out. Savings accounts let you move your money if rates rise elsewhere, but CDs do not.

Tools and methods to track your interest earnings

Most banks show your interest earnings in your monthly statement under a line item like "Interest Paid" or "Interest Earned." Online banks display it in your account dashboard, updated daily or weekly. You can also calculate it yourself using the formula: (Balance × APY ÷ 365) × Number of Days. For $10,000 at 4.5% APY over 365 days, that is ($10,000 × 0.045 ÷ 365) × 365 = $450.

If you want to compare what different banks would pay, use a savings calculator. You enter your balance, the APY, and the time period, and it shows you the total interest. These calculators assume the rate stays constant and you do not add or withdraw money—real life is messier, but the calculator gives you a reasonable estimate for comparison purposes.

Keep your statements. The interest you earn is taxable income, and your bank will send you a 1099-INT form at tax time if you earned $10 or more in interest during the year. You need that form to file your taxes correctly.

Frequently Asked Questions

Can I earn interest on interest?

Yes, if the bank compounds daily and you leave the money untouched. Each day, the bank calculates interest on your balance plus the interest already earned, then adds that to your account. Over time, this compounds into real money. A $10,000 balance at 4.5% APY compounded daily earns about $460 over a year instead of exactly $450, because of compounding.

What is the difference between APY and APR on a savings account?

APY includes compounding; APR does not. Banks are required to advertise savings accounts using APY because it shows the real rate you earn. APR is used for loans and credit cards. On a savings account, always compare APY to APY, never APR to APY.

Do I pay taxes on savings account interest?

Yes. Interest is taxable income. If you earn $10 or more in a calendar year, your bank sends you a 1099-INT form, and you report that interest on your tax return. The amount you owe in taxes depends on your tax bracket.

Is my interest safe if the bank fails?

Yes. The FDIC insures deposits up to $250,000 per depositor per bank. Your interest earnings are part of that $250,000 limit. If a bank fails, the FDIC pays you back, including any interest you earned up to the failure date.

Why do some banks pay almost no interest?

Traditional banks with physical branches have higher costs and less competition for deposits because customers are less likely to move their money. Online banks compete on rate because rate is their main selling point. If you keep money at a bank paying 0.01% when you could move it to a bank paying 4.5%, you are giving up hundreds of dollars per year for no reason.