BYTETOOLS

CD Calculator

Work out what a certificate of deposit pays at maturity, its true APY at any compounding frequency, and what an early withdrawal penalty would cost you.

$12,833.59
Value at maturity
$2,833.59
Interest earned
5.1162%
Effective APY
$250.00
Early withdrawal penalty

Year by year

PeriodInterest addedInterest to dateBalanceIf closed early
Year 1$511.62$511.62$10,511.62$10,261.62
Year 2$537.79$1,049.41$11,049.41$10,799.41
Year 3$565.31$1,614.72$11,614.72$11,364.72
Year 4$594.23$2,208.95$12,208.95$11,958.95
Year 5$624.63$2,833.59$12,833.59$12,583.59

The last column subtracts a penalty of 6 months of interest, calculated as deposit × rate ÷ 12 × months = $250.00. Many banks apply the penalty to the amount withdrawn rather than the full deposit, so treat this as an upper bound and read your CD disclosure.

Balances use A = P(1 + r/n)nt, or A = Pert for continuous compounding, and the APY is (1 + r/n)n − 1. Worked check: a 5% nominal rate is a 5.1162% APY compounded monthly, 5.1267% daily and 5.1271% continuously, and $10,000 at 5% compounded annually for five years reaches $12,762.82. Interest is shown before tax. Arithmetic only, not financial advice.

What is the CD Calculator?

The ByteTools CD Calculator compounds a deposit using A = P(1 + r/n)^(nt), or the continuous form Pe^(rt), and reports the maturity value, the interest earned and the effective APY behind the bank's quoted rate.

  • Seven compounding options including continuous compounding
  • Converts the quoted nominal rate into the true APY
  • Term entered in either years or months
  • Early withdrawal penalty priced in months of interest
  • Year-by-year interest, running total and closed-early value
  • Runs entirely in your browser — no rates fetched, nothing uploaded

How to use the CD Calculator

  1. 1

    Enter your deposit amount and the nominal interest rate the bank quotes.

  2. 2

    Choose how often the CD compounds — daily and monthly are the most common.

  3. 3

    Set the term, switching the unit between years and months as needed.

  4. 4

    Enter the early withdrawal penalty in months of interest from your CD disclosure.

  5. 5

    Read the maturity value, interest and APY, then check the year-by-year table including the early-exit column.

About the CD Calculator

The ByteTools CD Calculator compounds a deposit using A = P(1 + r/n)^(nt), or the continuous form Pe^(rt), and reports the maturity value, the interest earned and the effective APY behind the bank's quoted rate. Daily, weekly, monthly, quarterly, semi-annual, annual and continuous compounding are all available, because two CDs at the same headline rate do not pay the same amount.

It also prices the exit. Set the early withdrawal penalty in months of interest, the way CD disclosures state it, and the year-by-year table adds a column showing what you would walk away with if you broke the CD at that point.

Everything is computed locally in your browser with no data sent anywhere, so real deposit amounts are safe to enter. Interest is shown before tax, and the figures are arithmetic for comparison rather than financial advice.

Frequently asked questions

How is CD interest calculated?

With the compound interest formula A = P(1 + r/n)^(nt), where P is your deposit, r is the annual rate, n is how many times a year it compounds and t is the term in years. $10,000 at 5% compounded annually for five years grows to $12,762.82.

What is the difference between a CD's rate and its APY?

The rate is the nominal annual figure; the APY is what you actually earn once compounding is included. A 5% nominal rate is a 5.1162% APY compounded monthly and 5.1267% compounded daily, which is why APY is the only fair basis for comparison.

How much is an early withdrawal penalty on a CD?

Banks usually state it as a number of months of interest — often three months on short terms and six to twelve on longer ones. This tool prices it as deposit × rate ÷ 12 × months, which is an upper bound, since many banks apply the penalty only to the amount withdrawn.

Can you lose money on a CD?

You can lose interest, and on a long CD broken very early a penalty can bite into the principal. Inflation is the other risk: a CD paying less than the inflation rate loses purchasing power even though the balance goes up.

Is the interest shown here before or after tax?

Before tax. CD interest is normally taxed as ordinary income in the year it is credited, so apply your own marginal rate to the interest figures to see what you keep.

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