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CD Calculator

Estimate interest at maturity from an advertised APY or a nominal interest rate. The estimate assumes a fixed rate and interest left in the CD.

Certificate of deposit calculator

APY already includes compounding. Terms use months ÷ 12; actual bank maturity calculations may use exact calendar days.

Estimated interest at maturity$425.00on $10,000.00 over 12 months
Ending balance
$10,425.00
APY
4.25%

How CD interest is calculated

from APY:      ending = deposit × (1 + APY)^(months ÷ 12)
from nominal:  APY = (1 + rate ÷ n)^n − 1
interest       = ending − deposit
n              = compounding periods per year

A $10,000 deposit at 4.25% APY earns $425 over one modeled year. If 4.25% is instead a nominal rate compounded daily, the APY is about 4.34% and the estimated one-year interest is $434.13. Select the type of rate stated in the offer.

The estimate uses constant equivalent growth between dates. It does not reproduce a bank’s daily accrual, interest posting, cent rounding, leap-year convention or exact maturity date. Fees, taxes, changing rates and interim interest payouts are excluded. Zero months returns the original deposit with no interest.

Frequently asked questions

How is CD interest calculated?

For an advertised APY, estimated ending balance is deposit × (1 + APY)^(months ÷ 12). For a nominal annual interest rate, the tool first converts it to APY using the selected compounding frequency. Interest is ending balance minus deposit.

What is the difference between APY and interest rate?

APY includes compounding. Select APY when entering an advertised yield; applying compounding to it again would overstate interest. A nominal interest rate needs a compounding frequency. Compare the term, withdrawal conditions and minimum deposit as well as the yield.

Is CD interest taxable?

Interest in a taxable account is generally taxable under IRS interest-income rules. Reporting timing can depend on the CD, including original issue discount rules for some longer-term deposits. IRA treatment depends on the type of IRA. The calculator estimates interest before tax.

What happens if I withdraw early?

A CD may charge an early-withdrawal penalty; the amount and exceptions depend on its terms. This estimate assumes the deposit stays until maturity, with interest retained to compound. It does not deduct penalties or model interest paid out during the term.

Are CDs insured?

Eligible CDs at FDIC-insured banks fall under deposit insurance, generally $250,000 per depositor, per insured bank, per ownership category. The limit applies together with your other deposits in that category at the same bank, not separately to each CD.

Sources and updates

Methods and figures reviewed on . Provider rates and terms can change; check the linked source and your own account terms.

This calculator gives estimates for information only and is not tax, legal or financial advice. Actual outcomes depend on the assumptions, timing, taxes, fees and terms that apply to you. See how we calculate.