CD (Certificate of Deposit) Calculator

Use this professional CD calculator to estimate your maturity amount, interest earned, effective APY, taxes, and optional early‑withdrawal penalties. Designed for savers and financial planners who need fast, accurate, and accessible results on any device. This cd calculator updates instantly as you type.

Calculator

Enter principal, choose rate mode, set term and options. Results update automatically below.

The amount you deposit when opening the CD.
Choose interest input mode
APY includes compounding and represents the effective annual yield. Nominal rate must be paired with a compounding frequency (e.g., daily) to derive the effective yield.
%
Annual Percentage Yield, including compounding. Example: enter 5 for 5.00%.
Duration of the CD. Use months or years via the selector.
Interest payout or reinvestment
Reinvest (compound) adds earned interest to the balance, increasing future earnings. Payout monthly distributes interest to you without compounding.
Advanced options
%
Optional. Your marginal tax rate to estimate after-tax interest.
Optional. If you plan to withdraw before maturity, enter the month of withdrawal. 0 means no early withdrawal.
Typical penalties range from 3 to 12 months of interest on the principal. Check your bank’s disclosure.

Results

Maturity value
$0.00
Total interest earned
$0.00
Effective annualized return over term
0.00%
Input yield (APY)
—
After-tax interest (if tax set)
—
After-tax maturity (if tax set)
—
Early withdrawal balance (at month)
—
Penalty estimate
—
Net after penalty (before tax)
—
Net after penalty and tax (if tax set)
—

Notes: Results are estimates for planning. Actual bank methods may vary slightly. Penalties and taxes are approximations based on the inputs provided.

Data Source and Methodology

Primary reference: eCFR, Title 12 — Banks and Banking, Part 1030 (Truth in Savings), Appendix A — Annual Percentage Yield (APY) Formula. Latest version available at: https://www.ecfr.gov/current/title-12/chapter-X/part-1030/appendix-Appendix A to Part 1030.

All calculations in this tool follow the standard compound interest definitions and the APY relationship defined in these regulations. Where users choose “Paid out monthly,” monthly effective rates are derived from APY or the specified nominal/compounding pair.

Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.

The Formula Explained

1) APY from nominal rate and compounding m times per year: $$\mathrm{APY}=\left(1+\frac{i}{m}\right)^{m}-1$$ 2) Compound growth using APY over t years: $$A=P\,(1+\mathrm{APY})^{t}$$ 3) Compound growth using nominal i with m compounding periods per year over t years: $$A=P\left(1+\frac{i}{m}\right)^{m\,t}$$ 4) Effective monthly rate from APY or from nominal/compounding: $$r_{m}=(1+\mathrm{APY})^{1/12}-1\quad\text{or}\quad r_{m}=\left(1+\frac{i}{m}\right)^{m/12}-1$$ 5) If interest is paid out monthly (no reinvestment), total interest for M months: $$I=P \cdot r_{m}\cdot M,\qquad A=P+I$$ 6) Effective annualized return over the actual term (t years): $$\mathrm{EAR}_{\text{term}}=\left(\frac{A}{P}\right)^{1/t}-1$$ 7) After-tax maturity with tax rate τ applied to interest: $$A_{\text{after}}=P+(1-\tau)(A-P)$$ 8) Early withdrawal penalty estimate with p penalty months: $$\text{Penalty}\approx P\cdot r_{m}\cdot p,\qquad A_{\text{net}}=A_{\text{withdraw}}-\text{Penalty}$$

Glossary of Variables

P (Principal)
The initial deposit amount you place in the CD.
APY
Annual Percentage Yield (effective annual return including compounding).
i (Nominal rate)
Stated annual interest rate without compounding.
m (Compounding frequency)
Number of compounding periods per year (1, 2, 4, 12, 365).
t
Term in years; t = months / 12.
M
Term in months.
r_m
Effective monthly rate derived from APY or nominal+compounding.
A
Maturity value (principal plus interest).
I
Total interest earned over the period.
τ (tau)
Marginal tax rate as a decimal (e.g., 0.24 = 24%).
p
Penalty months of interest used for early-withdrawal estimate.

How It Works: A Step‑by‑Step Example

Suppose you deposit P = $10,000 at APY = 5.00% for M = 18 months (t = 1.5 years), with reinvestment (compound).

  1. Compute maturity using APY: A = P × (1 + APY)^t = 10,000 × 1.05^1.5 ≈ $10,759.37.
  2. Total interest I = A − P ≈ $759.37.
  3. Annualized return over the term: EAR_term = (A / P)^(1/t) − 1 ≈ 5.00%.
  4. If interest were paid out monthly instead, use r_m = (1 + 0.05)^(1/12) − 1 ≈ 0.4074% per month; I ≈ 10,000 × 0.004074 × 18 ≈ $733.32; A ≈ $10,733.32.

Frequently Asked Questions (FAQ)

How accurate is this cd calculator?

It applies standard formulas and the APY definition under Truth in Savings. Bank‑specific conventions may vary slightly, which can cause small differences.

Should I enter APY or nominal rate?

If your bank quotes APY, choose APY. If it quotes a nominal rate, select the bank’s compounding frequency to derive the effective yield.

What term length should I choose?

Match the CD’s advertised term. If your plan is to withdraw early, use the advanced early‑withdrawal fields for a penalty estimate.

How is tax handled in this tool?

The tool applies your marginal tax rate to interest to estimate after‑tax results. Taxes vary by jurisdiction and timing; consult a professional for advice.

Can penalties reduce my principal?

Yes, if accrued interest is less than the penalty, some banks deduct the difference from principal. The tool shows a net value that may fall below the initial deposit in such cases.

Does interest paid out monthly compound?

No. If you choose “Paid out monthly,” interest is not reinvested, so the maturity amount is lower than a compounding CD with the same rate and term.

What’s the best compounding frequency?

More frequent compounding yields slightly higher returns. Many banks compound daily. Always use the frequency stated by the bank for accurate estimates.

Tool developed by Ugo Candido. Content verified by CalcDomain Finance Editorial Team.
Last reviewed for accuracy on: .