CD Calculator — Estimate Certificate of Deposit Interest & Maturity

Enter your CD details to see interest earned and maturity value. Private by design—everything runs locally in your browser.

Inputs

Symbol is cosmetic; calculations are unitless.
APY is effective annual yield. APR is nominal; choose compounding below.
For APY, we derive a matching per-period rate using this frequency.

Results

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Formula: \( A = P\,(1+i)^{n} \) where \(i\) is the per-period rate and \(n\) the number of compounding periods. For APY \(e\), \( i = (1+e)^{1/m} - 1 \); for APR \(r\), \( i = r/m \).

How this CD Calculator works

Enter a principal, choose APY (effective) or APR (nominal), select compounding, and set the term. We compute the maturity value and total interest. The schedule shows end-of-year balances assuming no withdrawals.

Notes & Assumptions

  • Taxes and bank fees are not included.
  • Early withdrawal penalties vary by bank and are not modeled here.
  • For APY, compounding frequency is used to distribute the effective annual growth into per-period rates for scheduling.

Frequently Asked Questions

What’s the difference between APY and APR?

APY includes compounding over a year (effective rate). APR is nominal—compounding frequency determines the actual yield.

Can I enter partial terms?

Yes—use months or enter decimals in years (e.g., 1.5 years).

Is my data private?

Yes. Calculations run entirely in your browser.

5 Fun Facts about CDs

APY hides the compounding rate

Two CDs can both quote 5% APY, but one might compound daily and the other monthly. The daily one back-solves to a slightly lower nominal rate to reach the same APY.

Rate puzzle

Early withdrawal isn’t always “all interest”

Penalties are often “X months of interest”—not just forfeiting the last months’ earnings. Pulling out early can claw back interest you already earned.

Penalty quirk

Grace periods are short

Most banks give ~7–10 days after maturity to move the money before auto-renewal. Miss it and you might get rolled into a new term you didn’t want.

Timing alert

Ladders are built for surprises

Splitting into staggered CDs (laddering) keeps liquidity: one rung matures soon while others keep earning higher rates.

Liquidity trick

Interest may stop at maturity

If a matured CD auto-moves to checking, growth can halt immediately. Parking in a high-yield savings until you decide can keep earnings alive.

Keep it growing

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