CD Calculator
Calculate the maturity value and interest on a certificate of deposit.
Results update as you type.
About this calculator
A certificate of deposit (CD) pays a fixed interest rate in exchange for locking your money away for a set term. This calculator compounds your deposit at the stated rate and frequency to show the value at maturity, the total interest earned, the effective annual yield (APY), and — if you enter a tax rate — the interest you keep after tax.
The maturity value is deposit × (1 + rate ÷ n)^(n × years), where n is how often it compounds. For example, 10,000 in a 5-year CD at 4.5% compounded monthly grows to about 12,518, so you earn roughly 2,518 in interest, and the effective yield works out to about 4.59% APY — a little above the 4.5% nominal rate because of monthly compounding.
Use it to compare CD offers, to see how term length and compounding change the payoff, or to check whether a CD beats a high-yield savings account once you account for the lock-up. Remember CD interest is normally taxable each year, and cashing out early usually triggers an interest penalty that this calculator does not deduct.
Frequently asked questions
How is CD interest calculated?
The deposit compounds each period: maturity = deposit × (1 + rate ÷ n)^(n × years), where n is the compounding frequency. Interest earned is the maturity value minus your original deposit.
Should I compare CDs by APR or APY?
Compare by APY, because it already folds in the compounding frequency and reflects what you actually earn in a year. Two CDs with the same APR but different compounding will have slightly different APYs.
Is CD interest taxed?
Yes. Interest on a CD is generally taxable as ordinary income in the year it is credited, even if you do not withdraw it. Enter your marginal tax rate to see the after-tax interest, which is the number that matters for comparing a taxable CD with a tax-advantaged account.
What happens if I withdraw from a CD early?
Most CDs charge an early-withdrawal penalty, often several months of interest, which can wipe out much of your gain or even dip into principal. This calculator assumes you hold to maturity, so subtract any penalty yourself if you might cash out early.
Does a longer CD term always earn more?
A longer term earns more total interest at a given rate and often carries a higher rate, but it also locks your money up longer and exposes you to missing out if rates rise. Some savers use a CD ladder — staggered maturities — to balance yield and access.
How does a CD compare to a savings account?
A CD usually pays a higher, fixed rate in return for locking the money away for the term, while a savings account pays a variable rate you can withdraw any time. If you will not need the cash before maturity, the CD’s higher guaranteed APY often wins.
API — use this calculator from code
Call this calculator as a free JSON endpoint — no key required. Send the field values below as query parameters or JSON. Read the full API docs →
Endpoint
GET https://calculator.free/api/v1/cd/curl
curl "https://calculator.free/api/v1/cd/?deposit=10000&rate=4.5&years=5"JavaScript fetch()
const r = await fetch(
"https://calculator.free/api/v1/cd/?" + new URLSearchParams({
"deposit": "10000",
"rate": "4.5",
"years": "5"
}));
const data = await r.json();
console.log(data.results);Results are estimates for general guidance only, not financial, medical or tax advice.