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CD Calculator (Certificate of Deposit)

Calculate CD maturity values, interest earned, and APY with term comparison and CD laddering strategy analysis.

Tested tool guide Tested browser tools Checked August 16, 2026

What CD Calculator (Certificate of Deposit) does, with a checked example

A CD quote becomes comparable only after its deposit, stated annual rate, term, and compounding schedule are considered together. This calculator projects the balance at maturity and separates the gain from the original deposit, then calculates APY so differently compounded rates can be compared. Its term and ladder views help examine multiple maturities instead of one CD. The common trap is entering a bank's quoted APY as though it were a nominal rate; those are not interchangeable when compounding occurs more than once a year.

Worked example

A concrete input and expected output from the current implementation.

Input

Initial deposit: $1,000; annual interest rate: 4.00%; term: 12 months; compounding frequency: quarterly.

Expected output

Maturity value: $1,040.60; interest earned: $40.60; APY: 4.06%.

Each quarter earns 1.00%, so the balance is $1,000 x 1.01^4 = $1,040.60401. The gain is $40.60401, and the effective annual yield is 1.01^4 - 1 = 4.060401%; the displayed figures are rounded.

How the result is produced

1

Compound maturity calculation

For principal P, nominal annual rate r, n compounding periods per year, and term t in years, the standard projection is P(1 + r/n)^(n x t). Interest earned is the projected maturity balance minus P. APY is (1 + r/n)^n - 1, expressing the effective yield over one year.

2

Term and ladder analysis

The term comparison applies the supplied deposit and rate assumptions to each selected duration, showing how maturity value and earned interest change. Ladder analysis treats each allocation as a separate CD rung with its own term and rate, then organizes the maturity points. It does not predict rates available when matured rungs are renewed.

Good uses

  • Checking the maturity amount and interest on a 9-month bank CD before committing cash.
  • Comparing CDs with different stated rates and compounding frequencies on an APY basis.
  • Dividing a deposit among several CD terms to inspect a ladder's maturity schedule and projected interest.

Limits and checks

  • Confirm whether the entered percentage is a nominal annual rate or an APY. Feeding an APY into a nominal-rate field can overstate the result because compounding is applied again.
  • Unless explicitly included, early-withdrawal penalties, taxes, fees, and promotional conditions are outside the projection. Maturity value is not the amount available after an early exit.
  • Bank figures can differ because of day-count rules, exact opening and maturity dates, crediting frequency, and rounding. A month-based estimate may not match a calculation using actual days.

Common questions

Should I compare the interest rate or APY?

Use APY to compare annualized yields when CDs have different compounding schedules. Use projected interest dollars to compare what a particular deposit earns during its actual term. APY does not mean a short-term CD earns that percentage of principal before maturity; it expresses yield on an annual basis under the stated assumptions.

Does the ladder analysis include the rate after each CD renews?

No, unless a separate renewal rate is entered and displayed in the scenario. A ladder can identify when each rung matures and value the initial terms, but future CD offers are unknown. Treat any repeated-cycle total as assumption-driven, and review the initial maturity values independently.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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