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CD Calculator

Estimate what a certificate of deposit is worth at maturity from the deposit, APY or APR, compounding and term, with an early withdrawal penalty and tax on interest.

  • Free, no sign-up
  • Runs in your browser
  • Finance
Deposit and rate
For example 6, 12, 18 or 60. Up to 240 months.
The rate I know is
Banks usually advertise the APY, which already includes compounding.
Penalty and tax (optional)
For example 3 for "three months of interest". Check your bank's terms.

Read the guide How CDs Work: Interest, Penalties and CD Ladders

How to use the CD calculator

Enter the amount you plan to deposit and the term in months. Then choose which rate you know. Banks usually advertise the APY (annual percentage yield), which already includes the effect of compounding. Some list an APR or plain interest rate instead. Pick the compounding frequency from the account terms; daily and monthly are the most common.

Two fields are optional. The early withdrawal penalty is entered the way banks describe it, in months of interest, for example 3 for "three months of interest". The tax rate is the rate you expect to pay on the interest. Press Calculate to see the balance at maturity, the interest earned, both forms of the rate and, if you filled them in, the tax and the penalty. The table below shows the balance at the end of every month.

The method

APY and APR are linked by the number of compounding periods per year, n:

  • APY = (1 + APR / n)^n − 1
  • APR = n × ((1 + APY)^(1 / n) − 1)

The balance after t months is deposit × (1 + APY)^(t / 12). When the term is not a whole number of compounding periods, the last short period is assumed to earn the same effective rate, which is a close estimate.

The penalty is calculated as simple interest on the deposit at the APR: deposit × APR × penalty months / 12. Tax is applied only to the interest.

Worked example

You deposit 10,000 for 12 months at a 5% APR compounded monthly. The APY is (1 + 0.05 / 12)^12 − 1 = 5.1162%, so the CD grows to 10,511.62 and earns 511.62 in interest. With a 24% tax rate the tax is 122.79, leaving 388.83 of interest after tax. A penalty of three months of interest would be 10,000 × 0.05 × 3 / 12 = 125.

If the bank had quoted a 5% APY instead, a 12-month CD earns exactly 500, and the matching APR with monthly compounding is 4.8889%.

Good to know

  • Compare CDs by APY. Two CDs with the same APR but different compounding pay slightly different amounts; the APY already accounts for that.
  • Penalty rules vary. Some banks base the penalty on the amount withdrawn, some on days of interest, and some can take part of your deposit if you withdraw very early. The table shows what you would get back each month after the penalty.
  • Results are estimates. They assume the rate stays fixed for the whole term and that interest stays in the CD, and they do not include fees or inflation.

Frequently asked questions

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

The APR is the stated yearly interest rate before compounding. The APY is what you actually earn in a year once interest is added to the balance and starts earning interest itself. With monthly compounding, a 5% APR equals an APY of about 5.1162%.

Does the compounding frequency matter if I enter the APY?

Not for the balance at maturity, because the APY already includes compounding. The frequency is still used to show the matching APR and to work out the penalty, which banks usually base on the stated interest rate.

Can an early withdrawal penalty reduce my deposit?

Yes. If you withdraw before you have earned as much interest as the penalty, the rest comes out of your deposit. In the table, any month where the early withdrawal value is below your deposit shows this case.

Is CD interest taxed?

In many countries CD interest is taxed as ordinary income, often in the year it is credited rather than at maturity. Enter your expected tax rate to see an estimate of the interest you keep, and check your local rules for details.