CD Calculator

Calculate maturity value and interest earned. Convert APR ↔ APY using compounding frequency.

How to Use

  1. Enter your deposit amount (principal).
  2. Enter the rate and choose whether it’s APR or APY.
  3. Select compounding and term length (months/years).
  4. See maturity value, interest earned, and conversions in the results.
Results
Calculated in base terms; formatting may auto-scale for readability.
Maturity Value
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Interest Earned
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APY
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APR
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Assumptions: Fixed-rate CD
Inputs & Settings
Enter values; results update instantly. Share link only updates when you press “Share Link”.
Starting deposit amount (no additional deposits assumed unless enabled below).
APY already includes compounding; APR needs compounding to derive APY.
Common CD terms: 3, 6, 9, 12, 18, 24, 36, 60 months.
Used for APR ↔ APY conversion and growth when rate is entered as APR.
Show Work (step-by-step)
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Work is shown using standard compound interest notation (n = compounds per year, t = years).

Formulas (Reference)

This tool models a fixed-rate CD with compounding. Early withdrawal penalties, taxes, and fees are not included.

  • Compound growth (single deposit): A = P × (1 + r/n)^(n×t)
  • APY from APR: APY = (1 + APR/n)^n − 1
  • APR from APY: APR = n × ((1 + APY)^(1/n) − 1)
Where P = principal, A = maturity value, r = annual rate (decimal), n = compounding periods per year, t = years.

FAQ

APR vs APY — what’s the difference?

APR is the nominal annual rate. APY is the effective annual rate after compounding.

Why does compounding matter?

More frequent compounding increases APY for the same APR.

Does this include taxes or penalties?

No. This is a deterministic math model for growth and rate conversions only.

Tool Info

Last updated:

Updates may include additional compounding rules, contribution schedules, and edge-case validation.