What determines how much interest you'll make

The amount of interest your savings account earns depends on three things: the annual percentage yield (APY) the bank offers, how much money you keep in the account, and how long it stays there. A bank with a 4.5% APY will pay you roughly 4.5% of your balance per year—but the exact dollar amount changes based on your balance and how often the bank compounds interest (usually daily or monthly).

The APY varies widely. Online banks often offer 4% to 5.35% on savings accounts right now, while traditional brick-and-mortar banks may offer 0.01% to 0.5%. The difference between these rates is enormous: $10,000 earning 4.5% APY makes about $450 per year, while the same $10,000 at 0.01% makes $1 per year.

Your balance also matters. Interest compounds, meaning you earn interest on your interest. A $50,000 balance at 4.5% APY earns roughly $2,250 per year. A $5,000 balance at the same rate earns roughly $225 per year. The longer money sits untouched, the more compounding works in your favor.

Key Takeaways

  • The APY your bank advertises is the rate you'll earn annually, but the actual dollar amount depends on your balance and how often interest compounds.
  • Online banks typically offer 4% to 5.35% APY on savings accounts, while traditional banks often offer less than 1%.
  • You can calculate your earnings by multiplying your balance by the APY as a decimal (for example, $10,000 × 0.045 = $450 per year).
  • Interest compounds regularly—usually daily or monthly—so money left untouched grows faster than money you withdraw and redeposit.
  • The bank must disclose the APY before you open an account, so you can compare rates across institutions before deciding where to put your money.

How to calculate interest on your own balance

The basic formula is straightforward: multiply your account balance by the APY expressed as a decimal. If you have $25,000 in an account with a 4.5% APY, multiply $25,000 by 0.045. That gives you $1,125—roughly what you'll earn in a year if you don't add or withdraw money.

That calculation assumes the interest compounds annually, which is rare. Most banks compound daily or monthly, which means you earn slightly more because interest gets added to your balance regularly, and then you earn interest on that interest. The difference is usually small—maybe $10 to $30 per year on a $25,000 balance—but it adds up over time.

If you want to know what you'll earn over a specific number of months rather than a full year, divide the annual amount by 12 and multiply by the number of months. A $25,000 balance earning $1,125 per year earns about $94 per month ($1,125 ÷ 12 = $93.75). Over six months, that's roughly $562.

Why APY varies so much between banks

Banks set their own APY based on what the Federal Reserve charges them to borrow money, what they can earn by lending that money out, and how much competition they face for deposits. Online banks typically offer higher rates because they have lower overhead costs—no physical branches, fewer employees, less real estate. They pass those savings to customers in the form of higher APY.

Traditional banks with physical locations often offer lower rates because their costs are higher. They also rely on customer loyalty and convenience rather than competing on rate alone. Some banks offer promotional rates for new customers—for example, 5% APY for the first three months—then drop the rate afterward. Always check what the rate will be after any promotional period ends.

The Federal Reserve's interest rate decisions affect all banks. When the Fed raises its rate, banks typically raise their savings APY within weeks or months. When the Fed cuts rates, banks usually cut their APY as well. This means the rate you see today may not be the rate you earn six months from now.

How compounding frequency affects your earnings

Compounding is how often the bank adds interest to your balance. With daily compounding, the bank calculates interest each day and adds it to your account. With monthly compounding, it happens once a month. The more frequently interest compounds, the more you earn—but the difference is usually small.

Here's a concrete example: $10,000 at 4.5% APY compounded daily earns about $460 per year. The same $10,000 at 4.5% APY compounded monthly earns about $459 per year. The difference is $1. On larger balances or over longer periods, the gap widens slightly, but most savings accounts compound daily anyway, so this rarely matters in practice.

The bank must disclose the compounding frequency in the account disclosure document, usually called the Truth in Savings Act disclosure or account terms. You'll see it listed alongside the APY. If you're comparing two accounts with the same APY, daily compounding is marginally better, but the difference is negligible for most people.

What happens to interest if you withdraw money mid-year

Interest is calculated on your average daily balance or your balance on specific dates, depending on the bank's method. If you withdraw money partway through the year, you earn interest only on the balance you actually held. For example, if you keep $25,000 in the account for six months, then withdraw $15,000, you earn interest on $25,000 for those six months and on $10,000 for the remaining six months.

Some banks use the average daily balance method, which means they add up your balance each day and divide by the number of days in the period. Others use the daily balance method, calculating interest each day on whatever balance you have that day. Both methods penalize you for withdrawals, but the penalty is proportional to how much you withdrew and for how long.

If you plan to withdraw money during the year, ask the bank how they calculate interest. The difference between methods is usually small, but knowing the rule helps you understand why your actual earnings don't match the straightforward APY calculation.

Comparing savings accounts across different banks

The easiest way to compare is to list the APY, the compounding frequency, and any fees for each account you're considering. Most online banks have no monthly fees, but some traditional banks charge $5 to $15 per month if your balance falls below a minimum (often $500 to $2,500). A fee can wipe out months of interest earnings, so factor that in.

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's worth confirming. You can search the FDIC's BankFind tool on their website to verify.

Also check the bank's history of rate changes. Some banks cut their APY quickly when the Fed cuts rates but raise it slowly when the Fed raises rates. Others do the opposite. You can't predict future rates, but looking at a bank's past behavior gives you a sense of whether they're competitive or slow to move.

Why your actual earnings might differ from the advertised APY

The APY is an annual rate, so if you only keep money in the account for part of a year, you earn less. If you deposit $10,000 on July 1 and leave it until December 31, you've held it for roughly six months, so you earn about half the annual amount. At 4.5% APY, that's roughly $225 instead of $450.

Fees also reduce your earnings. If your bank charges a $10 monthly maintenance fee and you earn $40 in interest that month, your net gain is $30. Over a year, a $10 monthly fee costs you $120, which could wipe out most or all of your interest on a small balance.

Some banks also have minimum balance requirements to earn the advertised APY. If your balance drops below the minimum, you may earn a lower rate or no interest at all. Always read the account terms to see whether there are conditions attached to the APY you see advertised.

Frequently Asked Questions

Can I earn more interest by moving my money to a different bank?

Yes, if your current bank offers a much lower APY than competitors. Moving $25,000 from a 0.5% APY account to a 4.5% APY account means earning an extra $1,000 per year. The switch takes a few days and involves no cost to you. However, check whether your current bank has any early withdrawal penalties or minimum balance requirements before you move.

What's the difference between APY and APR?

APY includes compounding, while APR does not. For savings accounts, you want APY because it shows what you'll actually earn. APR is used for loans and credit cards. Banks must disclose APY for savings accounts, so you'll always see the right number.

Will my interest rate stay the same forever?

No. Banks change their APY based on Federal Reserve decisions and competition. Your rate could go up or down at any time. Some banks notify customers before a rate change, but they're not required to. Check your account statements or log into your online banking to see if your rate has changed.

How much money do I need to open a savings account and start earning interest?

Most online banks have no minimum deposit requirement. Some traditional banks require $100 to $2,500 to open an account. Once the account is open, you earn interest on whatever balance you maintain, even if it's $1. Check the bank's website or call to confirm their minimum before opening an account.

Is the interest I earn on my savings account taxable?

Yes. Interest income is taxable as ordinary income at your federal and state tax rates. Banks send you a 1099-INT form each January if you earned $10 or more in interest during the previous year. You report this on your tax return. This is one reason high-yield savings accounts are more valuable than low-yield accounts—the interest you earn is worth the tax burden.