CD Calculator

This simple, browser-based tool estimates the ending balance and interest income on a certificate of deposit. Enter the initial deposit amount, annual interest rate, compounding method, deposit term (in months), and marginal tax rate. (In this simplified model, interest is taxed at the end of the period.)

Initial deposit

Starting amount you deposit into the CD (currency assumed USD for display).

Interest rate (%)

Annual percentage. If “annually (APY)” is selected, this is APY; other options treat this as nominal APR.

Compound

Compounding convention. APY is an effective annual yield. Others use nominal APR with the chosen frequency; “continuously” uses continuous compounding.

Deposit length (months)

Term of the CD in months. Fractional months are allowed.

Marginal tax rate (%)

Percentage of interest taxed (simplified as a one‑time tax on total interest at maturity).

Output

End balance:

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Total interest:

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