Certificate of Deposit (CD) Calculator

Calculate maturity value, total interest, effective APY, estimated tax, and after-tax balance for a Certificate of Deposit — with an annual accumulation schedule.

Initial deposit ($)Interest rate (APR %)

Term

Unit

CompoundingMarginal tax rate (%)Federal + state marginal rate on interest income.

Maturity value

$11,442.48

Total interest$1,442.48

Effective APY4.594%

Estimated tax$317.35

After-tax balance$11,125.13

Results update as you type

Annual accumulation schedule
Year	Balance	Interest	Est. tax
1	$10,459.40	$459.40	$101.07
2	$10,939.90	$480.50	$105.71
3	$11,442.48	$502.58	$110.57

What this calculator does

This Certificate of Deposit calculator computes the maturity value, total gross interest, effective APY, estimated tax at your marginal rate, and after-tax balance — and shows an annual schedule of balance, interest, and tax for each year of the term.

Formula

Future value: FV = P × (1 + r ÷ m)^(m × t)

APY: APY = (1 + r ÷ m)^m − 1

Annual interest: interest_year = balance × APY

Tax: tax = marginal_rate × interest

Variable definitions

P — Principal — the amount you deposit at the start of the term.
r — Nominal annual interest rate as a decimal (e.g. 0.045 for 4.5%).
m — Compounding periods per year (365 daily, 12 monthly, 4 quarterly, 2 semi-annual, 1 annual).
t — Term length in years.
marginal_rate — Your federal/state marginal tax rate on ordinary income, as a percent.

Step-by-step calculation

Convert the annual rate from percent to decimal (divide by 100).
Divide the decimal rate by the number of compounding periods per year.
Add 1, then raise to the power of (periods × years) to get the growth factor.
Multiply by the principal — that's the maturity value.
Subtract the principal for total interest. APY uses the same formula with t = 1.
Multiply each year's interest by your marginal tax rate for the estimated tax.

Worked example

Deposit $10,000 at 4.5% APR, monthly compounding, 3 years, marginal tax rate 22%:

Periodic rate: 0.045 ÷ 12 = 0.00375 · Periods: 36 · Growth: (1.00375)^36 ≈ 1.14415
Maturity value: 10,000 × 1.14415 = $11,441.55
Total interest: $1,441.55 · APY: 4.594%
Estimated tax: 0.22 × 1,441.55 = $317.14
After-tax balance: 11,441.55 − 317.14 = $11,124.41

How to use this calculator

Enter your deposit amount, the CD's APR, the term, and the compounding frequency.
Enter your marginal tax rate for after-tax results (leave at 0 to see pre-tax only).
Review the annual schedule below to see balance and tax for each year.

Common mistakes

APR vs APY: APR is the nominal rate. APY includes compounding and is the right number to compare CDs.
Adding contributions: traditional CDs don't accept additional deposits. The calculator assumes a single deposit.
Ignoring early-withdrawal penalties: taking funds out before maturity usually forfeits several months of interest.

Frequently asked questions

›What is a CD (Certificate of Deposit)?

A CD is a savings product that holds a fixed amount for a fixed term in exchange for a guaranteed interest rate. Withdrawing early usually triggers a penalty of several months of interest.

›How is CD interest calculated?

CDs use compound interest. Final value = principal × (1 + rate/m)^(m × years), where m is the number of compounding periods per year (12 for monthly, 4 for quarterly, 1 for annual).

›What is APY?

APY (annual percentage yield) is the effective annual return after compounding. APY = (1 + rate/m)^m − 1. APY is the right number to compare CDs with different compounding frequencies.

›How are taxes on CD interest calculated?

CD interest is generally taxed as ordinary income in the year it's credited. The estimated tax shown here is your marginal rate × the year's interest. Consult a tax professional for your specific situation.

›Is CD interest taxable?

Yes, in most jurisdictions. CD interest is reported on a 1099-INT and taxed as ordinary income for U.S. federal returns, even if the CD has not yet matured.

›What is a CD ladder?

A CD ladder spreads deposits across CDs maturing at different times (e.g. 1, 2, 3, 4, 5 years). It blends higher long-term rates with periodic access to part of the money as each rung matures.

›Monthly vs quarterly vs annual compounding — does it matter?

Slightly. More frequent compounding produces a marginally higher APY for the same nominal rate. The difference grows with longer terms and higher rates.