The amount you earn depends on the bank's APY, how much you have saved, and how long the money sits there

Your savings account interest is calculated using the annual percentage yield (APY) the bank publishes. If you have $10,000 in an account with a 4.5% APY, you earn roughly $450 per year — but that money arrives in small deposits throughout the year, not in one lump sum. The exact amount also shifts if the bank changes its rate or if you add or withdraw money during the year.

The real number that matters is what your bank actually pays you. Log into your account online or call the bank directly and ask for the current APY on your specific account type. That rate is what you use to calculate your earnings. Banks are required to show the APY clearly on their website and in account disclosures, so you should be able to find it without asking — but calling gets you the fastest answer if you need it today.

Interest compounds, meaning you earn interest on the interest you already earned. Most savings accounts compound daily or monthly. Daily compounding pays slightly more than monthly, but the difference on a typical balance is a few dollars per year. The bank handles all the math; you do not have to do anything.

Key Takeaways

  • Your earnings equal your account balance multiplied by the APY, divided by 365 days — so a $5,000 balance at 4% APY earns roughly $200 per year.
  • The APY your bank advertises is the rate you should use; it already includes the effect of compounding, so you do not calculate that separately.
  • Interest rates change frequently, and your bank can lower the rate on your account with notice, so check your current APY every few months.
  • 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 balance.

How the calculation actually works

The formula is simple: balance × APY ÷ 365 = annual interest. If you have $20,000 at 4.5% APY, multiply $20,000 by 0.045 to get $900 per year. That $900 is divided into daily deposits, so you earn roughly $2.47 per day. The bank deposits this interest into your account automatically — you never have to request it.

If your balance changes during the year, the interest calculation changes too. A $10,000 deposit in July means you earn interest on the full amount for only six months of the year, not twelve. The bank tracks this automatically using the daily balance method: it calculates interest on whatever you have in the account each day, then adds it all up at the end of the month or quarter.

Compounding means the interest you earn starts earning interest itself. If your account compounds monthly, the bank adds your interest to your balance at the end of each month, and next month's interest is calculated on the larger balance. This effect is small on typical savings account balances — the difference between daily and monthly compounding on $10,000 at 4% APY is roughly $10 per year — but it works in your favor.

Why rates vary so much between banks

Online banks pay higher APY than traditional banks because they have lower overhead costs. They do not maintain physical branches, so they pass the savings to customers through higher rates. A high-yield savings account at an online bank might pay 4.5% APY, while the same bank's brick-and-mortar competitor pays 0.1% on a regular savings account. On a $50,000 balance, that difference is $2,200 per year.

Banks also change their rates based on what the Federal Reserve does. When the Fed raises its benchmark rate, banks typically raise savings account APY within weeks. When the Fed cuts rates, banks lower savings APY much more slowly — sometimes not at all for months. This means your rate today might not be your rate in six months.

Some banks offer promotional rates for new customers: a higher APY for the first few months, then a drop to their standard rate. Read the fine print to see when the promotional period ends and what the regular rate will be. If you move your money to chase promotions, you lose the interest you would have earned by staying put, so the math only works if the promotional rate is significantly higher.

Money market accounts and CDs pay differently

A money market account works like a savings account but usually pays a slightly higher APY in exchange for requiring a larger minimum balance — often $2,500 to $10,000. You earn interest the same way: balance × APY ÷ 365. The tradeoff is that you may have limits on how many withdrawals you can make per month without a fee.

A certificate of deposit (CD) locks your money away for a set term — three months, six months, one year, five years — and pays a fixed APY for that entire period. If you withdraw the money early, you pay a penalty that wipes out some or all of your interest. CDs typically pay more than savings accounts because the bank knows your money will stay put. A one-year CD might pay 5% APY while a savings account pays 4.5%, but you cannot touch the money without losing earnings.

What happens when rates drop

Banks can lower your savings account APY at any time with notice — usually 30 days. You will see the new rate in writing before it takes effect. If your bank drops the rate and you do not like it, you can move your money to another bank. There is no penalty for closing a savings account and transferring your balance elsewhere.

When rates drop across the industry, moving banks might not help much — most banks lower their rates around the same time. But if your bank drops its rate and others have not, switching saves you real money. Check rates at online banks like Marcus, Ally, or American Express Personal Savings every few months. If you find a bank paying 1% more APY, that is $100 per year on a $10,000 balance.

Tax on interest earnings

Interest you earn on a savings account is taxable income. The bank will send you a 1099-INT form in January if you earned $10 or more in interest during the year. You report this on your tax return as ordinary income and pay tax at your regular income tax rate.

This means a $50,000 balance earning 4% APY ($2,000 per year) will result in a tax bill. If you are in the 22% tax bracket, you owe roughly $440 in federal tax on that interest. The after-tax return is closer to 3.1%. This does not change how you should save — interest is still interest — but it is worth knowing that your actual take-home earnings are lower than the APY suggests.

Frequently Asked Questions

Does my savings account interest get paid monthly or yearly?

Banks deposit interest into your account monthly or daily, depending on the bank. You do not wait until the end of the year to see your earnings. Check your account statements to see when deposits appear — most online banks show interest deposits weekly or monthly.

What if I withdraw money mid-month — do I lose all the interest?

No. Banks use the daily balance method, so you earn interest on the money for the days it was in the account. If you have $10,000 for 20 days and then withdraw it, you earn interest on $10,000 for 20 days, not zero interest. The bank calculates this automatically.

Can a bank take away my interest after I earn it?

No. Once interest is deposited into your account, it is yours. The bank can lower the APY on future interest, but it cannot reduce interest you have already earned. The only exception is if you close the account and the bank assesses a fee that exceeds your balance — rare, but read the account terms.

Is there a limit to how much interest I can earn?

No limit exists on interest earnings. Earn as much as you want. The FDIC insures up to $250,000 per account type at each bank, so your balance is protected even if the bank fails — but your interest earnings do not count against that limit.

Why do some banks advertise "no fees" but still pay low interest?

No fees and high interest are separate things. A bank can charge no fees and still pay 0.01% APY because it does not need to attract deposits — it has other sources of funding. Online banks pay high APY because they compete on rate to attract deposits. Choose based on APY, not on fee waivers.