A certificate of deposit (CD) is one of the simplest ways to earn a predictable return on cash you do not need to touch. You hand a bank a fixed amount of money for a fixed length of time — say, $10,000 for 12 months — and in exchange the bank pays you a fixed annual percentage yield (APY). At the end of the term, you get your principal back plus the interest that has accrued. This CD calculator estimates exactly how much your deposit will be worth at maturity, how much interest you will earn, and what it would cost you to cash out early.
Unlike a savings account, where the rate can change and you can withdraw freely, a CD locks both the rate and the money. That predictability is the whole point: you know the ending balance the day you open the account. Adjust the deposit, term, and APY below and every figure updates instantly.
How to Use
- Enter your Initial Deposit — the amount you plan to put into the CD. Most banks have minimums of $500–$2,500, but high-yield CDs often start at $0.
- Choose the CD Term from the dropdown. Short terms (3–12 months) give you flexibility; longer terms (2–5 years) usually pay a higher APY but tie your money up longer.
- Type the advertised Interest Rate (APY). Use the APY, not the nominal rate — the APY already accounts for compounding, so the math matches what the bank will actually pay you.
- Optionally set the Early Withdrawal Penalty in months of interest. If you think you might need the money before maturity, this shows the cost. Leave it at 0 if you are certain you will hold to maturity.
The result card shows your initial deposit, the total interest you will earn, the balance at maturity (the highlighted number), the early-withdrawal penalty, and what you would net if you broke the CD early.
How CD Interest Is Calculated
Because the APY is already the effective annual yield, the maturity value is simply:
Maturity = Deposit × (1 + APY)^(Term in Years)
For a $10,000 CD at 4.5% APY held for 12 months, the term in years is 1, so maturity = $10,000 × 1.045 = $10,450, and the interest earned is $450. For a 24-month CD, the exponent becomes 2: $1,000,000 × (1.045)² = $1,092,025, earning $92,025 in interest over two years.
The early-withdrawal penalty is charged as a lump sum of several months of simple interest. On that same $10,000 at 4.5%, each month of interest is roughly $37.50 ($10,000 × 0.045 ÷ 12). A six-month penalty therefore costs about $225, reducing an early withdrawal to about $10,225 even though the CD has technically earned $450.
APY vs. Interest Rate: Why It Matters
Banks quote two numbers: the nominal interest rate and the APY. The APY folds in compounding frequency, so it is the real annual return you will receive. A CD advertised at 4.40% compounded daily can have an APY near 4.50%. Always compare CDs by APY, not by the nominal rate, and always enter the APY into this calculator — otherwise you will slightly overstate your earnings.
Choosing the Right Term
- 3–12 months are ideal for money you expect to need within a year, such as a sinking fund for a known purchase. Rates are lower, but your liquidity is quick.
- 18–24 months often sit on a steep part of the yield curve, paying meaningfully more than 12-month CDs without tying money up for many years.
- 3–5 years lock in the highest published rates, but if rates rise while your money is locked, you lose the chance to refinance at a better yield. A CD ladder (staggering several maturities) is the classic workaround, and this single-CD tool helps you size each rung.
Examples
Example 1 — The baseline 12-month CD. You deposit $10,000 into a 12-month CD at 4.5% APY. At maturity you receive $10,450, having earned $450 in interest with no penalty.
Example 2 — A six-month high-yield CD. You place $25,000 into a 6-month CD paying 5.0% APY. The term is half a year, so maturity = $25,000 × (1.05)^0.5 = $25,617.38, earning about $617.38 in just six months.
Example 3 — Breaking a CD early. On the same $10,000, 12-month, 4.5% CD, your bank charges a six-month interest penalty. If you withdraw after a few months, you forfeit about $225, netting roughly $10,225 instead of the full $10,450 — a reminder that CDs are designed to be held to maturity.
Example 4 — A $100,000+ deposit. A $1,000,000 two-year CD at 4.5% APY grows to $1,092,025 at maturity, earning $92,025. Keep in mind FDIC insurance caps at $250,000 per depositor per bank, so larger sums should be spread across institutions or ownership categories.
FAQ
How much interest will a CD earn?
Multiply your deposit by the APY raised to the term in years. A $10,000 CD at 4.5% APY for 12 months earns $450. Use this calculator and enter your deposit, term, and APY for an exact figure.
Is a CD better than a high-yield savings account?
A CD usually pays a higher fixed APY, but you cannot withdraw without a penalty. A high-yield savings account pays a variable rate and offers full liquidity. Choose a CD when you know you will not need the money for the full term.
What happens if I withdraw my CD early?
You forfeit a set number of months of interest — commonly 3–12 months, depending on the term. In rare cases the penalty can eat into your principal. Enter your bank's penalty in months in the Early Withdrawal Penalty field to see the exact cost.
Are CD interest rates fixed for the whole term?
Yes. That is the defining feature of a traditional CD: the APY is locked at opening and cannot change, even if the bank lowers rates for new customers. In return, you agree not to touch the money until maturity.
How much should I put in a CD?
Only money you can afford to lock up. A common rule of thumb is to keep your emergency fund in a liquid savings account and use CDs for savings earmarked for known future expenses. FDIC insurance covers up to $250,000 per depositor per bank.
What is the difference between APY and the interest rate?
The APY is the real annual return after compounding; the nominal interest rate is the raw rate before compounding. Always compare and enter APY — it is the number that actually hits your account.
Disclaimer
This CD calculator is provided for informational purposes only and does not constitute financial, banking, or tax advice. Estimates are based on the deposit, term, and APY you enter; actual CD offers, compounding methods, and early-withdrawal penalties vary by bank and may change. Interest earned may be taxable as ordinary income. Always confirm the exact terms and penalty schedule directly with your bank or credit union before opening a certificate of deposit.