What determines how much interest your savings account earns
The amount of interest you earn depends on three things: how much money you keep in the account, the annual percentage yield (APY) the bank offers, and how long the money stays there. A bank with a 4.5% APY will pay you more interest than one offering 0.01% APY, even if you deposit the same amount. The difference between these two rates is real — on $10,000 saved for a year, you'd earn roughly $450 at 4.5% versus $1 at 0.01%.
Banks set their own APY rates based on what the Federal Reserve charges them to borrow money. When the Fed's rates are high, banks offer higher APY to attract deposits. When Fed rates drop, bank APY drops too, sometimes within days. This means the rate you see today may not be the rate you earn six months from now.
The type of account also matters. A regular savings account typically earns less interest than a money market account or a certificate of deposit (CD). High-yield savings accounts, offered mostly by online banks, currently pay significantly more than traditional brick-and-mortar banks, though this gap narrows or widens depending on where the Fed's rates are heading.
Key Takeaways
- Interest earned = your account balance × the APY ÷ 12 months, though banks calculate and pay it monthly or daily depending on the account.
- Online banks and credit unions often offer higher APY than traditional banks because they have lower overhead costs.
- APY changes over time as the Federal Reserve adjusts its rates, so a 4.5% account today might pay 3.8% in six months.
- Money market accounts and CDs typically pay more interest than regular savings accounts, but CDs lock your money away for a set period.
- The bank compounds interest daily or monthly, meaning you earn interest on the interest you've already earned.
How banks calculate and pay your interest
Banks don't wait until the end of the year to pay all your interest at once. Instead, they calculate interest daily and add it to your account monthly, or sometimes daily. This process is called compounding — you earn interest on your original deposit, and then you earn interest on that interest.
Here's a concrete example: if you deposit $5,000 in an account with 4.5% APY, the bank calculates your daily interest by dividing 4.5% by 365 days. That's roughly 0.012% per day. On day one, you earn about $0.60. On day two, you earn interest on $5,000.60, not just $5,000. By the end of a month, you might have earned $18 to $19. By the end of a year, you'd have roughly $5,230 — the original $5,000 plus about $230 in interest.
The exact amount varies slightly depending on whether the bank compounds daily or monthly, and whether it credits interest on the first of the month or the last. These details matter more the larger your balance is, but they're usually spelled out in the account's terms and conditions.
Why online banks pay more than traditional banks
Online banks offer higher APY because they don't operate physical branches. A traditional bank pays rent, utilities, and salaries for tellers and loan officers in hundreds of locations. An online bank operates from a few data centers and customer service call centers. That lower cost means they can afford to pay you more interest and still make a profit.
Credit unions, which are member-owned rather than shareholder-owned, also tend to pay competitive rates. They're not trying to maximize profit for investors — they're trying to return value to members. Some credit unions pay rates as high as online banks, though availability depends on which credit union you join and where you live.
The trade-off is convenience. You can't walk into an online bank branch to deposit cash or speak to someone face-to-face. Most online banks accept mobile check deposits and transfers from other banks, but if you need to deposit physical cash regularly, a traditional bank or credit union branch may be more practical despite the lower rate.
How much interest you'll earn at different rates
The easiest way to see the difference is to look at specific numbers. Here's what you'd earn in one year on a $10,000 deposit at different APY rates, assuming the rate doesn't change:
| APY Rate | Interest Earned in One Year | Total Balance After One Year |
|---|---|---|
| 0.01% | $1 | $10,001 |
| 0.5% | $50 | $10,050 |
| 2% | $202 | $10,202 |
| 4% | $408 | $10,408 |
| 5% | $513 | $10,513 |
These numbers assume you don't add or withdraw money during the year and the rate stays constant. In reality, rates change, and most people add to their savings over time. If you deposit $200 per month into an account earning 4% APY, you'd earn more total interest because each new deposit starts earning when ready.
The difference between 0.01% and 4% is $407 per year on $10,000. Over five years, that gap grows to roughly $2,200. This is why shopping around for a higher APY matters, especially if you're keeping a large emergency fund or saving for a down payment.
When interest rates change and what that means for you
Banks adjust their APY rates frequently, sometimes weekly. When the Federal Reserve raises its benchmark rate, banks usually raise savings APY within days. When the Fed cuts rates, banks cut savings APY just as quickly — sometimes faster. This means a 4.5% account today could drop to 4% in a month if the Fed signals rate cuts are coming.
You don't lose interest you've already earned. If you earned $100 in interest at 4.5% APY last month, that $100 stays in your account. But going forward, your new interest is calculated on the new, lower rate. This is why it's worth checking your bank's current APY every few months. If your rate has dropped significantly and you have a large balance, moving to a bank offering a higher rate could mean hundreds of dollars more per year.
Some banks offer promotional rates — a higher APY for a limited time to attract new customers. These rates are real and you do earn that interest, but they usually drop after three to six months. Read the fine print to see when the promotional period ends and what the regular rate will be.
Money market accounts and CDs earn more, but with trade-offs
If you want to earn more interest than a regular savings account offers, you have two main options: a money market account or a certificate of deposit (CD).
A money market account is a hybrid between a savings account and a checking account. It typically pays higher interest than a regular savings account, sometimes 0.5% to 1% more. In exchange, it usually requires a higher minimum balance (often $2,500 or more) and limits how many withdrawals you can make per month. You can still access your money whenever you need it, but frequent withdrawals may trigger fees.
A certificate of deposit (CD) locks your money away for a set period — three months, six months, one year, or longer. In exchange, the bank pays you a higher interest rate, sometimes 1% to 2% more than a regular savings account. If you withdraw the money before the term ends, you pay a penalty, usually a few months' worth of interest. CDs make sense if you know you won't need the money for a specific period and want to lock in a rate before it drops.
How to find the current best rates
APY rates change constantly, so there's no single "best" rate that stays best for long. To find what's available right now, check the websites of online banks like Marcus, Ally, American Express Personal Savings, and Discover. Credit unions also publish their rates online. Compare the APY, the minimum balance required, and whether there are any fees for maintaining the account.
Some websites aggregate current savings rates across banks, though they don't always update when ready. Your own bank's website will show you its current rate, and you can call customer service to confirm. If your current bank's rate has dropped far behind what others offer, moving your money takes about a week and is usually free.
Remember that a slightly higher rate is only worth switching for if you have a substantial balance. Moving $2,000 from a 0.5% account to a 4.5% account earns you about $80 more per year — real money, but not life-changing. Moving $50,000 earns you about $2,000 more per year, which is worth the effort of switching.
Frequently Asked Questions
Can I lose money in a savings account?
No. The bank pays you interest; you don't pay the bank. Your balance only grows or stays the same. However, if inflation is high and your APY is low, the money's purchasing power decreases — $10,000 earning 0.01% APY loses value in real terms if inflation is 3%. This is why higher APY matters during high-inflation periods.
Is the interest I earn taxable?
Yes. Interest earned in a savings account is considered income by the IRS. Banks send you a 1099-INT form each January showing how much interest you earned the previous year. You report this on your tax return. The amount is usually small unless your balance is very large or your APY is high.
What happens to my interest if I withdraw money mid-month?
Most banks calculate interest daily, so you earn interest on the money you had in the account each day. If you deposit $5,000 on the first and withdraw $2,000 on the fifteenth, you earn interest on $5,000 for 14 days and $3,000 for the remaining days of the month. You don't lose the interest you've already earned.
Why do some banks offer 5% APY when others offer 0.5%?
Online banks and credit unions have lower operating costs, so they can afford to pay more. Traditional banks with many branches pay higher overhead and often pass lower rates to customers. Some traditional banks also assume customers won't shop around, so they don't need to offer competitive rates to keep deposits.
If I move my money to a higher-APY account, do I owe taxes on the interest I earned at my old bank?
You owe taxes on all interest earned in a calendar year, regardless of which bank paid it or whether you moved the money. The old bank reports the interest it paid you on a 1099-INT. You include that on your tax return even if the money is now somewhere else.