This CD calculator shows exactly what a certificate of deposit will be worth at maturity and how much interest you will earn along the way. Enter your deposit, the advertised APY, and the term in months to get an instant answer.
CDs are among the safest places to grow cash: rates are locked for the full term, and deposits are insured up to $250,000 per depositor, per bank, by the FDIC (or NCUA at credit unions). The trade-off is liquidity — withdrawing before maturity usually triggers a penalty — so matching the term to when you actually need the money matters as much as chasing the highest rate.
How CD Interest Is Calculated: APY vs APR
Banks advertise CDs using APY (annual percentage yield), which already includes the effect of compounding. That makes the maturity math clean:
- Value at maturity = deposit × (1 + APY)^(term in years)
- Total interest = value at maturity − deposit
APR (the nominal rate) is the rate before compounding. The relationship is APY = (1 + APR ÷ n)^n − 1, where n is the number of compounding periods per year. A CD compounding daily at a 4.40% nominal rate yields about 4.50% APY. Because APY already bakes compounding in, two CDs with the same APY pay the same interest regardless of whether they compound daily or monthly — the compounding frequency only changes the underlying nominal rate.
Early Withdrawal Penalties and CD Laddering
Breaking a CD before maturity costs you interest, and the penalty scales with term length. Typical penalties:
- Terms under 12 months: about 3 months of interest
- Terms of 1–3 years: about 6 months of interest
- Terms of 4–5 years: 12 months of interest or more
CD laddering solves the liquidity problem without giving up long-term rates. Split your money across staggered maturities — for example, $20,000 split into five $4,000 CDs maturing in 1, 2, 3, 4, and 5 years. As each CD matures, reinvest it into a new 5-year CD. After the ladder is built, a CD matures every year, giving you annual access to cash while most of your money earns the longer-term rate.
Example: $10,000 in a 12-Month CD at 4.5% APY
Deposit $10,000 into a 12-month CD paying 4.5% APY.
- Value at maturity: $10,000 × (1.045)^1 = $10,450.00
- Total interest earned: $450.00
Stretch the same rate to an 18-month term and the balance grows to $10,000 × (1.045)^1.5 = $10,682.54 — $682.54 in interest. Compare that with a high-yield savings account at 4.0%: after 12 months you would have about $10,400, and the bank could cut the rate at any time. The CD’s $50 edge comes with a rate guarantee, but withdrawing three months early with a 3-month interest penalty would erase roughly $112 of the earnings.
Frequently Asked Questions
How is CD interest calculated?
Multiply your deposit by (1 + APY) raised to the term in years. A $5,000 CD at 4% APY for 24 months grows to $5,000 × (1.04)^2 = $5,408, earning $408 in interest. Because APY already includes compounding, no further adjustment is needed.
What is the difference between APY and APR on a CD?
APR is the nominal annual rate before compounding; APY is the actual yearly yield after compounding. A 4.40% APR compounded daily equals about a 4.50% APY. Banks quote CDs in APY, so always compare offers using APY, not APR.
What happens if I withdraw a CD early?
You pay an early withdrawal penalty, usually forfeiting a set number of months of interest — commonly 3 months for terms under a year and 6–12 months for longer terms. If the CD has not yet earned that much interest, the penalty can eat into your principal at some banks.
Are CDs FDIC insured?
Yes. CDs at FDIC-member banks are insured up to $250,000 per depositor, per bank, per ownership category. Credit union CDs (share certificates) carry equivalent NCUA insurance. Amounts above the limit can be protected by spreading deposits across multiple institutions.
What is a CD ladder?
A CD ladder splits your savings across CDs with staggered maturity dates — for example, equal amounts in 1- through 5-year terms. Each year one CD matures, and you reinvest it at the long end. You keep regular access to a portion of your cash while earning long-term rates on most of it.
How do I calculate CD interest by rate?
Enter the CD rate as an APY and multiply your deposit by (1 + APY) raised to the term in years. At a 5% rate, a $10,000 CD held two years grows to $10,000 × (1.05)^2 = $11,025, earning $1,025. If the bank quotes a nominal APR instead, convert it to APY first, since APY reflects compounding.