Basics
Compound Interest Calculator
Compound interest calculator: project growth from a lump sum, monthly deposits, or both — or set a savings goal and find your monthly deposit.
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CD Calculator (Certificate of Deposit) (2026)
Estimate maturity payouts, accumulated interest, and effective returns for bank certificates of deposit with fixed APYs and customized CD laddering terms.
Quick Answer: A Certificate of Deposit (CD) is a federally insured time-deposit account offering a fixed interest rate in exchange for locking up funds for a specified term. Returns are governed by the Annual Percentage Yield (APY) under the federal Truth in Savings Act (Regulation DD). When APY is known, final maturity value is calculated as A = P · (1 + APY)^(months / 12), while daily or monthly compounding from a nominal rate r uses A = P · (1 + r/n)^(n·t). For a standard $10,000 deposit in a 12-month CD with a benchmark 4.00% APY, your account matures at exactly $10,400.00, yielding $400.00 in guaranteed interest.
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Last reviewed: October 2026
Calculation Methodology: CD Calculator (Certificate of Deposit) (2026)
Mathematical Formula
A = P · (1 + APY)^(t) | Interest = A - P
A = Maturity balance (Principal + Interest)
P = Initial deposit amount
APY = Annual Percentage Yield in decimal form (e.g., 0.04 for 4.00%)
t = Term in years (Months ÷ 12)
When calculating from nominal rate (r) with compounding frequency (n): A = P · (1 + r/n)^(n·t) and APY = (1 + r/n)^n - 1.
Verified Worked Example (Benchmark)
Benchmark Parameters: Initial Deposit (P) = $10,000 · Annual Percentage Yield (APY) = 4.00% (0.04) · Term = 12 Months (1.0 Year).
- Term in Years (t): 12 months ÷ 12 = 1.0 year.
- Maturity Multiplier: (1 + 0.0400)^1.0 = 1.040000.
- Final Account Value at Maturity (A): $10,000 × 1.040000 = $10,400.00.
- Total Guaranteed Interest Earned: $10,400.00 - $10,000.00 = $400.00.
CD Ladder Illustration (Split $30,000 across 3 Terms at 4.00% APY):
- Bucket 1 (12 Months, $10,000): Matures at $10,400.00 ($400.00 interest).
- Bucket 2 (24 Months, $10,000): Matures at $10,816.00 ($816.00 interest).
- Bucket 3 (36 Months, $10,000): Matures at $11,248.64 ($1,248.64 interest).
- Total Ladder Value: $32,464.64 ($2,464.64 total interest earned with rolling liquidity every 12 months).
Primary Statutory Sources & Authorities
- FDIC National Deposit Rates and Limits — Official weekly national average deposit rates for 1-month to 60-month retail certificates of deposit.
- Consumer Financial Protection Bureau (CFPB) Regulation DD — Truth in Savings Act statutory standards for Annual Percentage Yield (APY) disclosures and early withdrawal penalty rules.
- Federal Deposit Insurance Corporation (FDIC Insurance Limits) — Statutory deposit insurance coverage of up to $250,000 per depositor, per insured institution.
Frequently Asked Questions
Primary source guidance on rules, formulas, and regulations.
A Certificate of Deposit (CD) is a specialized savings instrument offered by banks and credit unions that pays a guaranteed, fixed interest rate in exchange for keeping your principal locked for a defined term (ranging from 1 month to 5 years or longer). CDs are backed by federal deposit insurance (FDIC or NCUA) up to $250,000 per institution.
If you withdraw your money before the CD reaches maturity, the bank assesses an early withdrawal penalty. Penalties are typically calculated as a set number of months of interest (for example, 3 to 6 months of interest on a 1-year CD, or up to 12 months on a 5-year CD). In some cases, this penalty can reduce a portion of your initial principal if redeemed early in the term.
A CD ladder divides your savings into equal portions across CDs with staggered maturity dates (e.g., 1-year, 2-year, 3-year, 4-year, and 5-year CDs). As each CD matures every year, you reinvest the proceeds into a new 5-year CD at prevailing rates. This strategy provides regular annual liquidity while capturing the higher yield associated with longer-term deposits.
A CD is better if interest rates are expected to decline, because it locks in your guaranteed APY for the full term. A High-Yield Savings Account (HYSA) offers variable interest rates that fluctuate with Federal Reserve policy, but provides daily liquidity and immediate access to your emergency cash without penalty.
Yes. Interest earned on a CD is considered taxable ordinary income by the IRS in the calendar year it is credited to your account, even if you do not withdraw the funds until the CD matures in a later year. The issuing bank reports this interest to you and the IRS on Form 1099-INT.
When a CD matures, banks offer a brief grace period (typically 7 to 10 calendar days). During this window, you can withdraw your principal and interest, transfer funds, or change the term. If you take no action, most institutions automatically roll the balance into a new CD of the same duration at the bank's current default renewal rate.