What a CD earns depends on the rate, the amount you deposit, and how long you lock the money away

A certificate of deposit (CD) pays you a fixed interest rate for keeping your money in the account for a set period—usually three months to five years. The longer you commit, the higher the rate tends to be. A $10,000 CD at 4.5% annual percentage yield (APY) for one year earns $450 in interest. The same $10,000 at 5.25% APY for two years earns roughly $1,076 total (because you earn interest on your interest in year two). The math is straightforward: multiply your deposit by the APY, then multiply by the number of years.

The catch is that rates change constantly, and they vary widely between banks. A high-yield online bank might offer 5.0% APY on a one-year CD while a traditional bank down the street offers 2.5%. Over a year, that 2.5% difference costs you $250 on a $10,000 deposit. Shopping around matters more than the account type itself.

Key Takeaways

  • CD earnings are calculated by multiplying your deposit amount by the annual percentage yield (APY) and the number of years the money stays locked in.
  • Longer CD terms almost always pay higher rates than shorter ones, so a five-year CD typically earns more than a one-year CD at the same bank.
  • Online banks and credit unions often pay 1% to 2% more APY than traditional brick-and-mortar banks on the same CD term.
  • Early withdrawal penalties can erase months or years of interest earnings, so only deposit money you won't need before the maturity date.

How the math works: principal, rate, and time

CD interest is usually calculated using compound interest, which means you earn interest on the interest you've already earned. Most banks compound daily or monthly, though the difference is small on shorter terms.

For a simple example: $5,000 at 4.0% APY for one year earns $200. If that same CD compounds monthly, you earn slightly more—about $204—because each month's interest gets added to the balance before the next month's interest is calculated. The formula banks use is: Final Amount = Principal × (1 + APY/Compounding Periods)^(Compounding Periods × Years). You don't need to calculate it yourself; the bank shows you the exact amount you'll earn when you open the account.

The real variables you control are the deposit amount and the term length. A $25,000 deposit at 5.0% for two years earns roughly $2,550 in interest. The same $25,000 at 5.0% for one year earns roughly $1,250. Doubling the term doesn't double the earnings, but it does add significantly more money.

Why longer terms pay more—and when that matters

Banks pay higher rates for longer commitments because they want to keep your money invested for a predictable period. A five-year CD at 5.5% APY pays more than a one-year CD at 4.75% APY at the same bank. On a $10,000 deposit, that's the difference between earning $475 in year one (at 4.75%) and $550 in year one (at 5.5%).

But locking money away for five years only makes sense if you won't need it. If you withdraw early, most banks charge a penalty—often three to twelve months of interest. Withdraw from a five-year CD after two years and you might lose $550 in interest, leaving you with less money than you started with after accounting for the penalty. Read the penalty terms before you commit.

Some people use a CD ladder to balance higher rates with access to their money. You buy multiple CDs with different maturity dates—one that matures in one year, one in two years, one in three years, and so on. As each one matures, you can withdraw the money or roll it into a new CD at whatever the current rate is. This spreads your money across different rate environments instead of betting everything on one term.

How bank choice affects your total earnings

The difference between a 3.0% APY and a 5.0% APY CD is $200 per year on a $10,000 deposit. Over five years, that's $1,000 in lost earnings just by choosing the wrong bank. Online banks and credit unions consistently pay 1% to 2% more than traditional banks because they have lower overhead costs.

Compare rates across at least three to five institutions before you deposit. Most banks publish their current CD rates on their websites, and rate-comparison sites like Bankrate, DepositAccounts, and NerdWallet update daily. The highest-paying CD today might not be the highest-paying CD next month, but checking before you commit takes fifteen minutes and can add hundreds of dollars to your earnings.

Also check whether the bank is FDIC-insured (for banks) or NCUA-insured (for credit unions). This protects your deposit up to $250,000 if the institution fails. A slightly higher rate at an uninsured institution isn't worth the risk.

What happens to your earnings at maturity

When your CD reaches its maturity date, the bank adds all the interest you've earned to your account. You then have a window—usually seven to ten days—to decide what to do with the money. You can withdraw it, move it to a savings account, or roll it into a new CD.

If you don't do anything and the bank's policy allows it, many institutions automatically renew your CD at the current rate for the same term. This is convenient if rates haven't changed much, but if rates have dropped significantly, you might lock in a lower rate without meaning to. Read your CD agreement to see whether automatic renewal is the default, and set a calendar reminder for a few days before maturity so you can shop rates again.

Early withdrawal penalties and how they work

The penalty for withdrawing before maturity varies by bank and by term length. A three-month CD might charge thirty days of interest as a penalty. A five-year CD might charge twelve months of interest. Some banks charge a flat fee instead—$25 or $50—though this is less common.

The penalty is deducted from your interest earnings first. If you've earned $300 in interest and the penalty is $200, you get $100. If the penalty exceeds your interest, the bank deducts the difference from your principal. You end up with less money than you deposited, which defeats the purpose of saving.

Before you open a CD, ask the bank for the exact penalty amount in writing. Don't assume you know it. And only deposit money you're confident you won't need until the maturity date. If there's any chance you'll need the funds, a high-yield savings account—which has no withdrawal penalties—might be a better choice, even though the rate is usually slightly lower.

Frequently Asked Questions

How much interest does a $10,000 CD earn in one year?

It depends on the rate. At 4.0% APY, you earn $400. At 5.5% APY, you earn $550. The difference between banks can be $100 to $150 on a $10,000 deposit for the same one-year term, so shopping around matters.

Do I pay taxes on CD interest?

Yes. CD interest is taxed as ordinary income in the year you earn it. The bank sends you a 1099-INT form at tax time showing how much interest you earned. If you're in a higher tax bracket, the after-tax return on your CD is lower than the stated APY.

Is a CD better than a savings account?

CDs usually pay 0.5% to 1.5% more APY than savings accounts, but your money is locked away. If you need access to your funds, a high-yield savings account is more flexible. If you're saving for a specific goal months or years away, a CD locks in a higher rate and removes the temptation to spend the money.

What's the difference between APY and APR on a CD?

APY (annual percentage yield) includes compound interest, so it's the actual return you'll earn. APR (annual percentage rate) does not. Banks are required to show you the APY, which is the number that matters for comparing CDs.

Can I add money to a CD after I open it?

No. CDs are fixed-amount accounts. Once you open one, you can't deposit more money into it. If you want to save additional money at the same rate, you'd need to open a separate CD.