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US-specific calculator

US CD Calculator

Estimate certificate of deposit interest, maturity value, effective APY, after-tax interest, and the cost of cashing out before maturity.

$
%
months
%
months
months interest
Maturity value
$10,459.40
Interest earned
$459.40
Effective APY
4.594%
A $10,000 US CD at 4.50% for 12 months grows to $10,459.40. That is $459.40 of interest before tax and $358.33 after a 22.0% tax estimate. With an early withdrawal after 6 months, the penalty estimate is $112.50, leaving an after-tax value of $10,089.40.
Maturity$10,459.40

Interest schedule

US CD yearly interest schedule
YearInterestTaxEnding balanceAfter-tax value
1$459.40$101.07$10,459.40$10,358.33

How this CD calculator works

Enter the deposit, nominal annual interest rate, term, and compounding frequency. The calculator converts that rate into an effective APY, compounds the balance month by month, and estimates taxes on interest separately from the CD balance.

The early withdrawal section models a common CD penalty format: a stated number of months of interest. Actual bank terms vary, so check the disclosure before opening or breaking a CD.

Need the plain-English version first? Read the US CD guide.

Formula and assumptions

The calculator converts the nominal annual rate into an effective annual yield, then into an equivalent monthly growth rate so every schedule row uses the same compounding logic.

  • APY: (1 + rate / periods)^periods - 1, where periods are daily, monthly, quarterly, or annually.
  • Monthly balance: each month adds rounded interest to the prior balance and tracks cumulative tax on interest.
  • Early withdrawal: the penalty is estimated as initial deposit times nominal monthly rate times the penalty months.

Frequently asked questions

Is this CD calculator US-specific?

Yes. It is designed around US certificate of deposit terminology, including early withdrawal penalties expressed as months of interest and tax estimates on interest earned.

What is the difference between the interest rate and APY?

The interest rate is the nominal annual rate. APY is the effective annual yield after compounding, so more frequent compounding can produce a slightly higher APY.

Can a CD early withdrawal penalty reduce my principal?

Some CDs can charge a penalty larger than the interest earned so far. This calculator shows the penalty separately so you can see whether the early withdrawal still leaves a gain.