CD (Certificate of Deposit) Calculator

Follow these steps to project exactly what your CD will earn:

1. Enter your deposit amount. The lump sum you plan to commit. Most banks require $500 or $1,000 minimum; some jumbo CDs require $100,000 for the highest tier rates.
2. Enter the annual rate. Use the APY from the bank’s rate page rather than the APR — APY already accounts for compounding within the year and is what you actually earn. If the bank only displays an APR, the APY will be very slightly higher.
3. Select the term. The lock-up period in months. Match this to your need: don’t put down-payment money or your emergency fund in a 5-year CD just to chase a 30 basis-point yield bump.
4. Select compounding frequency. Most banks compound daily; some compound monthly. Check the rate disclosure or call to confirm. The difference between daily and monthly is real but small — typically a few dollars on a $10,000 deposit.

The calculator returns three numbers: interest earned over the full term, the final balance at maturity (your principal plus all interest), and the effective APY — the true annualized return after compounding, which is the right number to use when comparing offers from different banks.

One thing this tool does not model: early withdrawal penalties. Those typically run 60–365 days of interest depending on term length, and on a CD you’ve held for less than the penalty period, the penalty can eat into your principal. Always read the bank’s penalty schedule before you sign.

A certificate of deposit trades flexibility for a guaranteed rate. You hand the bank or credit union your money for a fixed term — 3 months, 18 months, 5 years — and in return you get a rate higher than a savings account, with one catch: pull the money out before the term ends and you forfeit some of the interest as an early withdrawal penalty.

That trade exists because banks need predictable funding. A regular savings-account holder can drain the balance any morning; a CD holder can’t. Knowing your $10,000 will sit until October 2027 lets the bank lend that money out long-term, and they pay you a premium for the certainty. This is also why longer terms usually pay more — except when the yield curve is inverted, as it has been periodically through the 2024–2026 cycle. In an inverted curve, a 6-month CD sometimes pays more than a 5-year CD because banks expect rates to drop and don’t want to lock in long-duration deposits at today’s rates.

Every CD at an FDIC-member bank is insured up to $250,000 per depositor, per institution, per ownership category. Credit-union CDs get the same coverage from the NCUA. That makes CDs one of the lowest-risk dollar-denominated investments you can hold — meaningfully safer than money market funds, which aren’t FDIC-insured, and orders of magnitude safer than stocks or bond funds.

A few flavors are worth knowing. Traditional bank CDs are what most people open. No-penalty CDs let you withdraw early without losing interest, but pay slightly less. Brokered CDs, sold through investment accounts like Schwab or Fidelity, often pay more than bank CDs and can be sold on a secondary market — but their value fluctuates if you sell before maturity. Bump-up CDs let you raise your rate once during the term if rates climb. Each makes sense in a different rate environment.

One strategy this calculator pairs well with: a CD ladder. Instead of putting $50,000 into a single 5-year CD, you split it into five $10,000 CDs maturing 1, 2, 3, 4, and 5 years out. Each year one matures and you reinvest at whatever rate is current. You get the higher long-term yields while keeping a fifth of your money accessible every twelve months.

Disclaimer: This calculator is for educational purposes only and does not constitute financial advice. APYs vary by institution and change frequently. Always confirm the rate, term, and penalty schedule directly with your bank before depositing.

CD interest uses the standard compound interest formula — the same equation that powers savings accounts, mortgages, and bond pricing:

A = P × (1 + r ÷ n)^(n × t)

Variable	Meaning	Units	Typical Range
A	Final balance at maturity	dollars	—
P	Principal (initial deposit)	dollars	$500–$250,000
r	Annual interest rate	decimal (4.75% → 0.0475)	0.005–0.06
n	Compounding periods per year	integer (daily=365, monthly=12, quarterly=4, annually=1)	1–365
t	Term length	years (6 months = 0.5)	0.25–5

Interest earned = A − P

Effective APY = (1 + r ÷ n)ⁿ − 1

The intuition: each period, the bank credits interest on your current balance — which now includes the interest from previous periods. Daily compounding means interest is credited 365 times a year, and each day a tiny bit of interest earns interest of its own. The more frequently you compound, the higher the effective return — but the gains diminish quickly. On $10,000 at a 4.75% rate over one year:

• Annual compounding (n=1): final balance $10,475.00 — effective APY 4.750%
• Quarterly (n=4): final balance $10,483.53 — effective APY 4.835%
• Monthly (n=12): final balance $10,485.48 — effective APY 4.855%
• Daily (n=365): final balance $10,486.43 — effective APY 4.864%

The jump from annual to monthly is about $10.48. The jump from monthly to daily is only $0.95. This is why most banks settled on daily compounding as the marketing standard — it gives the highest displayable APY, but the actual extra dollars beyond monthly are minimal.

Example 1: $10,000 at 4.75% for 1 year, daily compounding

P = $10,000  |  r = 0.0475  |  n = 365  |  t = 1

A = $10,000 × (1 + 0.0475 ÷ 365)^(365 × 1)
A = $10,000 × 1.04864
A = $10,486.43

Interest earned: $486.43  |  Final balance: $10,486.43  |  Effective APY: 4.864%

Example 2: $50,000 at 4.25% for 5 years, daily compounding

P = $50,000  |  r = 0.0425  |  n = 365  |  t = 5

A = $50,000 × (1 + 0.0425 ÷ 365)^(365 × 5)
A = $50,000 × 1.23675
A = $61,837.54

Interest earned: $11,837.54  |  Final balance: $61,837.54  |  Effective APY: 4.341%

Notice how compounding amplifies returns over time: at 4.25% simple interest, five years would earn just $10,625. The extra $1,212.54 comes purely from interest earning interest.

Example 3: Short-term vs long-term — the inverted-curve dilemma

You have $25,000 to lock up. Bank A offers a 12-month CD at 5.00%. Bank B offers a 24-month CD at 4.50%. Both compound daily.

Option	Term	Final balance	Interest earned
Bank A (1-year @ 5.00%)	12 months	$26,281.69	$1,281.69
Bank B (2-year @ 4.50%)	24 months	$27,354.21	$2,354.21

Bank B earns more in absolute dollars because the money is working twice as long. But Bank A’s higher rate means that at the end of year 1, it has produced $131.07 more interest than Bank B will have produced by the same point ($26,281.69 vs $26,150.62). The right choice depends on your view of where rates are going. If 1-year CDs are still paying ~5% in twelve months, rolling Bank A wins. If rates drop to 3.5%, locking Bank B’s 4.50% for the full 24 months wins.