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CD Interest Rate Calculator

This CD interest rate calculator estimates interest earned and the balance at maturity from a deposit, an APY or APR, and a term. Use APY when the bank already quotes yield, because that yield is not compounded again. Use APR when you have a nominal rate and want daily, monthly, quarterly, or annual compounding applied once.

The opening certificate-of-deposit principal.

APY already includes compounding. This calculator will not compound it again.

Rate type

Banks often compound monthly or daily. Frequency is unused while APY is selected so interest is not double-compounded.

CD interest estimate

Interest earned
$450.00
Ending balance
$10,450.00
Effective APY used
4.50%
Term
1 year
Year-by-year CD balance
PeriodStartInterestEnd
Year 1$10,000.00$450.00$10,450.00

Gross interest only. Early-withdrawal penalties, fees, and taxes are not deducted. This is not a bank offer, rate lock, or tax advice.

Advertiser disclosure: A finance partner link will show here when it is live. We may earn a commission if you use it. This is not a loan offer, and the calculator result does not change.

How to use

  1. Enter the deposit amount. That is the opening certificate principal, before interest.
  2. Choose APY (includes compounding) when the offer already states yield. Choose APR (apply compounding) only for a nominal rate.
  3. Enter the term and set the unit to months or years. Twelve months and one year are the same term.
  4. If you chose APR, set compounding to daily (365 periods), monthly (12), quarterly (4), or annually (1). That menu does not change an APY result.
  5. Read interest earned, ending balance, and effective APY. Penalties, fees, and taxes are not deducted.

Formula

With APY, ending balance = deposit × (1 + APY) ^ years, and interest = ending balance − deposit. Convert months with years = months ÷ 12. With APR, convert first: effective APY = (1 + APR ÷ n) ^ n − 1, where n is 365 for daily, 12 for monthly, 4 for quarterly, or 1 for annually. Grow the deposit with that APY. Do not run compounding a second time after you enter APY.

Example. $10,000 at 4.50% APY for 12 months is $10,000 × 1.045 = $10,450.00, so interest is $450.00. The same deposit at 4.50% APR compounded monthly uses n = 12, an effective APY of about 4.59%, interest of $459.40, and an ending balance of $10,459.40. For 18 months at 4.50% APY, years = 1.5, interest is $682.54, and the balance is $10,682.54. Year 1 of that term earns $450.00; the last 6 months earn $232.54.

Frequently asked questions

What is the difference between APY and APR on a CD?

APY (annual percentage yield) is the effective yearly return after compounding. APR (annual percentage rate) is the nominal rate before compounding. On this page, $10,000 at 4.50% APY for 12 months earns $450.00 and ends at $10,450.00. The same deposit at 4.50% APR compounded monthly earns $459.40 and ends at $10,459.40, because the effective APY is about 4.59%. Banks usually advertise APY. Enter APY when that is the quote, and do not compound it again.

How often do CDs compound, and which setting should I use?

This calculator uses 365 periods for daily, 12 for monthly, 4 for quarterly, and 1 for annually. Those counts matter only when Rate type is APR. On a $10,000 deposit at 4.50% APR for 12 months, daily compounding earns $460.25 (about 4.60% APY), monthly earns $459.40 (about 4.59%), quarterly earns $457.65 (about 4.58%), and annually earns $450.00 (4.50% APY). While APY is selected, the compounding menu is ignored so the quoted yield is not applied twice.

Are early-withdrawal penalties included?

No. The interest and ending balance assume you hold the certificate to the term you entered. Breaking a CD early often costs a set number of days or months of interest, and some banks can take principal if accrued interest is not enough. Read the account disclosure before you open or cash a CD. This page does not subtract that penalty.

Is this a bank CD offer or a locked rate?

No. Quick Tools is not a bank, credit union, or broker. Nothing here is an offer, solicitation, or rate lock. Published CD rates change, may require a minimum deposit, and can differ by term. Use the numbers only to estimate interest from a rate you already saw.

How do I estimate CD interest from APY and term?

Turn the term into years (months ÷ 12). Ending balance = deposit × (1 + APY) ^ years, and interest = ending balance − deposit. $10,000 at 4.50% APY for 12 months is $10,000 × 1.045 = $10,450.00, so interest is $450.00. For 18 months, years = 1.5: interest is $682.54 and the balance is $10,682.54. Year 1 of that schedule earns $450.00 (balance $10,450.00); the remaining 6 months earn $232.54.

What does the year-by-year table show?

Each row is up to one year of growth at the effective APY. A 12-month CD is a single row from the deposit to the maturity balance. A longer term adds a row per year, and a partial final year is labeled with the leftover months. Start, interest, and end on those rows are gross figures. They do not subtract penalties or tax, and they match the summary when you add the interest column.

Is CD interest taxed?

This calculator shows gross interest before tax. In the U.S., CD interest is generally taxable as ordinary income in the year it is credited, even if you do not withdraw it, unless the CD is in a tax-advantaged account. Withholding, state tax, and reporting rules vary. This is not tax advice; check IRS guidance or a tax professional.

Does the term unit change the math?

Only through the length of the term. Twelve months and 1 year are the same span, so a 4.50% APY on $10,000 produces $450.00 of interest either way. Eighteen months is 1.5 years. The rate type and, for APR, the compounding frequency change the yield; the months-versus-years menu does not.

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