What you earn depends on the bank's rate, how much you deposit, and how long the money sits there

The amount of interest you earn in a savings account is calculated by multiplying your balance by the annual percentage yield (APY) the bank offers, then dividing by 365 days. If you keep $10,000 in an account with a 4.5% APY for a full year, you earn roughly $450 before taxes. If you deposit $10,000 mid-year, you earn half that. The actual dollar amount changes every month because interest compounds — meaning you earn interest on the interest you already earned — so your balance grows slightly faster than simple math suggests.

The catch is that APY varies wildly between banks. A traditional bank might offer 0.01% APY on a savings account, while an online bank might offer 4.5% or higher on the same $10,000. That difference means $1 versus $450 per year on the same deposit. Banks set their own rates based on what the Federal Reserve charges them to borrow money, competition from other banks, and how much they want to attract deposits. Rates change frequently — sometimes weekly — so the 4.5% you see today might be 4.2% next month.

Key Takeaways

  • Interest earned equals your balance multiplied by the APY, divided by 365, so a $10,000 deposit at 4.5% APY earns about $450 per year.
  • APY varies from under 0.01% at traditional banks to 4.5% or higher at online banks, making bank choice the biggest factor in how much you earn.
  • Interest compounds daily at most banks, meaning you earn small amounts of interest on interest, which speeds up growth slightly.
  • Your earnings are taxed as ordinary income, so you owe federal income tax on the full amount you earn, and state tax if your state has one.
  • Rates change frequently and are not locked in, so the APY you see when you open an account may be lower a few months later.

How compounding changes your earnings over time

Compounding means the bank calculates interest on your balance, adds it to your account, then calculates next month's interest on the new, larger balance. Most banks compound daily, which is the fastest option. On a $10,000 balance at 4.5% APY compounded daily, you earn about $1.23 on day one. On day two, you earn interest on $10,001.23, not $10,000. The difference is tiny at first — less than a penny — but it accelerates over months and years.

Over a full year, daily compounding adds roughly $23 to your earnings compared to simple interest (interest calculated once per year on the original balance). Over five years, the difference grows to about $120. The longer your money sits in the account, the more compounding matters. This is why moving money to a higher-APY account, even if only by 1%, can add hundreds of dollars over several years on a large balance.

Why different banks offer different rates

Banks borrow money from the Federal Reserve at a rate set by the Fed's policy committee. When the Fed raises its rate, banks pay more to borrow, so they raise the rates they offer on savings accounts to attract deposits. When the Fed lowers its rate, banks lower savings rates too — sometimes within days. This is why savings account APY climbed from near-zero in 2021 to 4.5% or higher in 2023 and 2024: the Fed raised its benchmark rate sharply to fight inflation.

Online banks typically offer higher APY than traditional banks because they have lower overhead costs — no physical branches, fewer employees — so they can afford to pay depositors more. A Chase or Bank of America savings account might earn 0.01% APY, while an online bank like Marcus or Ally offers 4.5% or higher on the same deposit. Credit unions sometimes offer competitive rates too, though they vary by institution. Shopping around for the highest APY can mean the difference between earning $10 and $450 per year on the same $10,000.

How taxes reduce what you keep

Interest earned in a savings account is taxed as ordinary income at your federal tax rate. If you earn $450 in interest and your federal tax bracket is 22%, you owe $99 in federal income tax on that interest. If your state has an income tax, you owe that too — usually at a lower rate than federal. This means the $450 you earned might shrink to $330 or $340 after taxes, depending on your tax bracket and state.

The bank reports your interest earnings to the IRS on a 1099-INT form if you earn $10 or more in interest during the year. You must report this on your tax return even if the bank does not send a form. If you earn less than $10, no form is issued, but you still owe tax on the interest. The only way to avoid this tax is to keep money in a tax-advantaged account like a Roth IRA or 529 plan, though these have contribution limits and withdrawal rules.

Comparing rates across account types and banks

High-yield savings accounts (HYSA) at online banks currently offer the highest APY for everyday savings, ranging from 4.0% to 4.75% depending on the bank and the current rate environment. Money market accounts often offer similar rates but may require a higher minimum balance. Traditional savings accounts at brick-and-mortar banks offer much lower rates, typically under 0.1% APY. Certificates of deposit (CDs) sometimes offer slightly higher rates than savings accounts, but your money is locked in for a set term — usually three months to five years — and you pay a penalty if you withdraw early.

The difference between a 0.01% savings account and a 4.5% HYSA is enormous. On $50,000, you earn $5 per year at 0.01% APY but $2,250 per year at 4.5% APY — a difference of $2,245. Even moving from a 2.0% account to a 4.5% account saves you $1,250 per year on the same balance. Rates change frequently, so check your current bank's rate against online options every few months. Many people keep money in a low-rate account simply because they opened it years ago and never checked alternatives.

What happens when rates drop

When the Federal Reserve lowers its benchmark rate, banks lower savings account APY within days or weeks. A 4.5% APY that was competitive in 2024 might drop to 3.5% or lower if the Fed cuts rates. Your existing balance does not earn the old rate — the new, lower rate applies immediately. This is why locking in a high rate through a CD makes sense if you believe rates will fall. A one-year CD at 4.5% guarantees that rate for 12 months, even if savings account rates drop to 2.0% during that time.

If you have money in a low-rate account and rates rise, your bank does not automatically raise your rate. You have to move the money to a new account or switch banks. This is why many people earn far less than they could: they set up an account years ago and never revisited it. Checking your current APY against online options once or twice per year takes 10 minutes and can save hundreds of dollars annually.

How much you need to deposit to make interest worthwhile

There is no minimum deposit required to earn interest, but the amount you deposit determines whether the interest is worth your time. At 4.5% APY, a $1,000 deposit earns about $45 per year, or $3.75 per month. A $10,000 deposit earns $450 per year, or $37.50 per month. A $100,000 deposit earns $4,500 per year. For most people, keeping an emergency fund of three to six months of expenses in a high-yield savings account makes sense because the interest is a bonus on top of the safety and liquidity. Keeping $500 in savings earns so little interest that the APY barely matters — focus on finding an account with no fees and easy access instead.

Some banks offer higher APY tiers based on your balance. You might earn 4.5% on balances up to $100,000 and 4.0% on anything above that, or vice versa. Read the fine print when comparing banks to see whether the rate you see applies to your balance size. A few banks offer promotional rates for new customers — 5.0% APY for the first three months, then 4.5% after — so timing your deposit can matter if you are moving a large sum.

Frequently Asked Questions

Do I have to pay taxes on savings account interest?

Yes. Interest earned in a savings account is taxed as ordinary income at your federal tax rate, plus state income tax if your state has one. The bank reports interest of $10 or more on a 1099-INT form. You owe tax on all interest, even if no form is issued. The only exception is interest earned in tax-advantaged accounts like Roth IRAs, which have contribution limits and withdrawal rules.

Can I lock in a savings rate so it does not drop?

No, savings account rates are variable and can change anytime. A certificate of deposit (CD) locks in a rate for a set term — three months to five years — but your money is locked in too, and you pay a penalty if you withdraw early. If you expect rates to fall, a CD protects you. If you expect rates to rise, a savings account keeps your options open.

Why does my bank pay almost no interest?

Traditional banks like Chase and Bank of America offer very low rates — often under 0.1% APY — because they attract deposits through branch locations and brand recognition, not competitive rates. Online banks like Marcus and Ally have no branches, so they pass savings to customers through higher APY. Switching to an online bank can increase your earnings from $10 per year to $450 per year on the same $10,000 deposit.

How often does the bank add interest to my account?

Most banks compound and deposit interest daily, meaning they calculate interest every day and add it to your balance. Some banks compound monthly or quarterly. Daily compounding is better because you earn interest on interest more frequently. The difference is small — a few dollars per year on most balances — but it adds up over time.

What if I withdraw money mid-year?

Interest is calculated on your average daily balance, so withdrawing money reduces the amount you earn for the rest of the year. If you deposit $10,000 on January 1 and withdraw $5,000 on July 1, you earn interest on $10,000 for six months and $5,000 for six months, which equals roughly $225 at 4.5% APY instead of $450. Some banks calculate interest differently, so check your account terms.