CD Calculator
Estimate certificate-of-deposit interest and maturity value from disclosed APY and exact term dates.
Content updated August 2, 2026
This is an APY-based maturity estimate. It excludes taxes, bonuses, early withdrawals, penalties, stepped or variable rates, institution-specific rounding, and automatic renewal.
A certificate of deposit usually trades access to deposited money for a stated term and yield. This calculator uses the institution's disclosed annual percentage yield and the exact number of calendar days between the entered dates to estimate interest left on deposit until maturity.
APY already reflects the relationship between interest and compounding over an annualized period. Use the disclosed APY rather than a nominal rate, and compare the estimate with the account agreement because actual day-count, rounding, penalties, rate steps, and renewal terms can differ.
The CD formula
Maturity value = P × (1 + APY/100)^(d/365); Interest = Maturity value − PP = starting deposit in the selected currency · APY = disclosed annual percentage yield · d = exact calendar days from deposit through maturity in this model.
Worked example
A $10,000 deposit earning a disclosed 4.5% APY for 365 days has a modeled maturity value of $10,450.00 and modeled interest of $450.00, assuming all principal and interest stay on deposit.
Assumptions, rounding, and limitations
Assumptions
- The entered APY is constant for the entire term.
- Principal and all interest remain on deposit until the maturity date.
- The term uses exact calendar days between two valid date-only values and an annualization basis of 365 days.
- No deposits, withdrawals, penalties, bonuses, fees, or interest distributions occur during the term.
- All money inputs and outputs use the selected currency unit.
Rounding: Day count is an exact whole calendar-day difference. Growth is calculated at floating-point precision and currency displays use up to two decimal places; an institution may round paid interest differently.
Limitations
- Supports deposits up to 1 trillion, APY from 0% to 100%, and terms from 1 to 36,600 days.
- Does not model nominal rates, separate compounding or crediting schedules, leap-year APY disclosure choices, tiered or stepped rates, variable or market-linked returns, early-withdrawal penalties, taxes, bonuses, calls, grace periods, or renewals.
- The estimate is not an account disclosure, statement, insurance determination, or guaranteed payout.
Sources
- Appendix A to Regulation DD — Annual Percentage Yield Calculation — Consumer Financial Protection Bureau
- Shopping for a Certificate of Deposit? — Federal Deposit Insurance Corporation
- Truth in Savings — Federal Deposit Insurance Corporation
Rearranging the Regulation DD APY formula
Regulation DD defines APY from principal, interest earned, and days in the term. Rearranging that relationship gives the modeled term growth: principal multiplied by (1 + APY) raised to days divided by 365.
The calculation assumes principal and interest remain on deposit for the complete term. The CFPB rule notes that institutions use actual term days for APY disclosures, which is why this tool asks for two dates rather than approximating every month as the same length.
Account terms still control the real payout
FDIC guidance says CD agreements can include early-withdrawal penalties, automatic renewal, stepped or variable rates, call provisions, and rules about when interest is paid. Those terms are not captured by one fixed-APY estimate.
Review the maturity date, grace period, renewal instructions, interest-payment method, and penalty formula before opening or closing an account. A quoted APY also does not by itself establish that every deposit is insured.
Frequently asked questions
▶Should I enter the interest rate or APY?
Enter the institution's disclosed APY. APY reflects interest and compounding on an annualized basis; a nominal interest rate is not interchangeable with it.
▶Why does this calculator use exact dates?
Regulation DD APY calculations use days in the term. Exact calendar dates capture different month lengths and leap days.
▶Does the result subtract an early-withdrawal penalty?
No. Penalty methods vary by agreement, and this calculation assumes funds remain on deposit until maturity.
▶Does this handle stepped-rate or market-linked CDs?
No. It models one constant disclosed APY. Products with changing rates, calls, or market-dependent returns need their contract-specific cash flows.
▶Will the CD automatically renew at maturity?
That depends on the account agreement. This calculator stops at the entered maturity date and does not model a renewal or grace period.
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Open calculator →Disclaimer: CD Calculator results are estimates for general information and education only, and are not financial, tax, legal or medical advice. Verify important decisions with a qualified professional.