The amount you earn depends on three things: how much you deposit, what rate the bank offers, and how long the money sits there

A savings account earns interest by paying you a percentage of your balance each month or year. That percentage is the Annual Percentage Yield (APY). If you deposit $10,000 in an account with a 4.5% APY, you earn roughly $450 per year — though the exact amount depends on how often the bank compounds interest (usually daily or monthly) and whether you add or withdraw money during the year.

The real number that matters is what you'll actually see in your account after a specific time. A high-yield savings account at 4.5% APY will earn you more than a traditional bank account at 0.01% APY, but the difference only shows up over months and years. After one year with $10,000, the high-yield account grows to about $10,450. The traditional account grows to about $10,001.

Interest compounds, which means you earn interest on your interest. If you leave that $450 in the account, next year you earn 4.5% on $10,450, not just the original $10,000. Over decades, this compounds into real money. Over months, it barely moves the needle.

Key Takeaways

  • Your earnings equal your balance multiplied by the APY, divided by 12 for a monthly estimate, though compounding changes the exact figure slightly.
  • A $10,000 deposit at 4.5% APY earns about $450 per year; at 0.01% APY it earns about $1 per year.
  • Banks compound interest daily or monthly, meaning you earn small amounts of interest on the interest you already earned.
  • Moving money in or out of the account changes your earnings, because interest is calculated on your average or ending balance depending on the bank's method.
  • APY rates change over time and vary widely between banks, so the rate you see today may not be the rate you earn next month.

How to calculate your own earnings

The basic formula is: Balance × APY ÷ 12 = Monthly earnings (approximate). If you have $25,000 at 4.5% APY, you earn roughly $93.75 per month. Multiply that by 12 and you get $1,125 per year.

This is an approximation because banks compound interest, usually daily. Compounding means the bank calculates interest on your balance, adds it to your account, then calculates next month's interest on the new, slightly larger balance. Over a year, this compounds into a number slightly higher than the straightforward formula gives you. For most savings accounts, the difference is small — usually less than $5 on a $25,000 balance — but it exists.

If you want the exact number, your bank's website or statement shows your actual interest earned. You can also use an online savings calculator and enter your balance, APY, and the number of months you plan to keep the money there. The calculator accounts for compounding automatically.

Why the APY you see today might not be the APY you earn tomorrow

Banks change their APY rates frequently, sometimes weekly. When the Federal Reserve raises or lowers interest rates, banks adjust their savings account rates within days or weeks. A high-yield savings account offering 4.5% today might offer 4.0% next month if the Fed signals it will cut rates.

Your earnings are locked in only for the interest already credited to your account. Future interest is calculated at whatever rate the bank is currently offering. This is different from a certificate of deposit (CD), where the rate is fixed for the entire term — six months, one year, five years, whatever you choose.

If you want to know what you'll earn over the next year, check the current APY, calculate based on that, and understand that the actual number will likely be different. Banks publish their rate history on their websites, so you can see whether a particular bank tends to raise or lower rates.

How deposits and withdrawals change what you earn

Banks calculate interest on either your average daily balance or your ending balance, depending on the bank's method. If you deposit $10,000 on the first of the month and withdraw $5,000 on the 15th, the two methods produce different results.

With average daily balance, the bank counts your balance as $10,000 for 14 days and $5,000 for 16 days, then averages those. With ending balance, the bank only looks at what you have on the last day of the month. Most banks use average daily balance, which is slightly more generous to you if you withdraw money mid-month.

The practical effect: if you're moving money in and out frequently, your actual earnings will be lower than the formula suggests, because you're not earning interest on money that isn't there. If you deposit $10,000 and when ready withdraw $5,000, you've earned interest on roughly $7,500 for the month, not $10,000.

Comparing earnings across different account types

High-yield savings accounts, money market accounts, and certificates of deposit all earn interest, but at different rates and with different rules. A high-yield savings account might offer 4.5% APY with no restrictions. A money market account might offer 4.3% APY but require a higher minimum balance. A one-year CD might offer 5.0% APY but lock your money away for 12 months.

Over one year, $10,000 earns $450 in the high-yield account, $430 in the money market account, and $500 in the CD. The CD wins on rate, but if you need the money before the year is up, you pay an early withdrawal penalty that usually wipes out most or all of your interest. The high-yield account gives you access to your money anytime without penalty.

The choice depends on whether you need the money soon. If you're saving for something more than a year away, a CD locks in a higher rate. If you might need it sooner, a high-yield savings account keeps your options open.

What happens to your earnings if rates drop

If you're earning 4.5% APY and the Fed cuts rates, your bank will lower your APY within weeks. Your existing balance still earns interest at the new, lower rate. You don't lose the interest you already earned — that stays in your account — but future interest accrues at the lower rate.

This is why the timing of when you open an account matters. If you open a high-yield savings account when rates are at their peak, you lock in that rate only until the bank changes it. If rates are falling, you might want to move money into a CD to lock in the current rate for a fixed period. If rates are rising, a savings account lets you benefit from the increases.

Checking your bank's current APY every few months helps you decide whether to stay put or move your money to a bank offering a better rate. Switching banks is free and takes a few days.

The real impact of interest over time

Interest earnings feel small month to month but compound into real money over years. A $50,000 deposit at 4.5% APY earns $2,250 per year. Over five years, with interest compounding, you earn roughly $12,000 in total interest. Over 20 years, you earn roughly $65,000 in total interest — your balance nearly doubles.

The longer your money sits in the account, the more the compounding effect matters. This is why starting early with savings, even small amounts, creates a significant difference by retirement. A $100 monthly deposit at 4.5% APY grows to roughly $73,000 over 30 years, with about $37,000 of that being interest you earned.

The flip side: if you're earning 0.01% APY at a traditional bank, that same $100 monthly deposit grows to roughly $36,000 over 30 years, with only about $180 being interest. The difference between a high-yield account and a traditional account is roughly $37,000 in this scenario — the cost of not shopping around for a better rate.

Frequently Asked Questions

How often does the bank pay me interest?

Most banks credit interest monthly, though some do it daily or quarterly. Monthly is standard. The interest shows up in your account as a deposit, and from that point forward you earn interest on that interest too. You don't have to do anything to receive it.

Can I lose money in a savings account?

No. Your balance can only stay the same or grow. Interest is always positive. However, inflation can reduce what your money buys — if inflation is 3% and you're earning 2% APY, your purchasing power declines slightly each year. This is why higher APY matters more in high-inflation environments.

What's the difference between APY and APR?

APY (Annual Percentage Yield) includes compounding, so it's the real rate you earn. APR (Annual Percentage Rate) does not include compounding. For savings accounts, always look at APY. APR is used for loans and credit cards, where it works against you instead of for you.

Do I have to pay taxes on savings account interest?

Yes. Interest earned is taxable income. Your bank sends you a 1099-INT form at the end of the year if you earned more than $10 in interest. You report this on your tax return. The higher your APY and balance, the more you owe in taxes on the interest.

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

No limit on interest itself. However, the FDIC insures savings accounts up to $250,000 per depositor per bank. If you have more than that, the excess is not insured against bank failure. Interest earnings don't count toward this limit — only your principal deposit does.