CD Calculator

How to use

1. 1Pick a common CD term (3-month, 6-month, 1-year, 5-year, etc.) to seed an example rate, or just type your own term in months.
2. 2Choose how the bank quotes the rate: APY (most US CDs under Regulation DD) or a nominal APR with an explicit compounding frequency.
3. 3Enter the deposit amount and pick a currency. The maturity value and total interest update instantly.
4. 4Turn on Model an early withdrawal to see what you would receive if you broke the CD before maturity, including a 3, 6, 12, or 18 month penalty preset.
5. 5Turn on Model income taxes and enter your federal and state marginal rates to see the after-tax interest and after-tax APY.
6. 6Click Show monthly schedule for a month-by-month interest and balance projection. Use Copy summary to grab a plain-text block for a budget or personal finance journal.

About this tool

CD Calculator projects the maturity value of a fixed-rate certificate of deposit and the interest it earns, supports both APY and nominal APR quotes, models early withdrawal penalties the way US banks actually charge them, and reports after-tax yield once you supply your federal and state marginal income tax rates. Most US banks quote CDs in APY (the effective annual yield after compounding, required by Regulation DD under the Truth in Savings Act), but some quote a nominal APR with an explicit compounding frequency, so the tool offers both inputs and converts between them. In APY mode the maturity formula is A = P * (1 + APY)^t, where t is the term in years, which is the same expression a bank's disclosure statement uses. In APR mode the tool first computes the equivalent APY using APY = (1 + APR/n)^n - 1 for the chosen compounding frequency (or APY = e^APR - 1 for continuous compounding) and then applies the same maturity formula, so APY-quoted CDs and APR-quoted CDs always sit on an apples-to-apples basis when you compare them. The results panel reports the maturity value, total interest earned, the effective APY actually used, the equivalent nominal APR for the selected compounding cadence, the total return percent over the term, and the time-weighted annualized return for off-by-a-month terms. The optional early withdrawal section computes the penalty exactly as most US banks describe it on their CD disclosures: k months of simple interest on principal at the nominal rate, where k is typically 3 months for terms under a year, 6 months for 1-year CDs, 12 months for 2 to 4 year CDs, and 18 months for 5+ year CDs. The tool also surfaces the case where the penalty exceeds the interest earned to date, because real institutions are allowed to reduce principal to cover the shortfall and that detail surprises customers who break a CD shortly after opening it. The optional tax section accepts federal and state marginal income tax rates separately, reports the taxes owed on the CD's interest, the after-tax interest, the after-tax maturity value, and the after-tax APY, with a basis-points readout of how much yield the taxes ate. Eight common term presets (3 months, 6 months, 9 months, 1 year, 18 months, 2 years, 3 years, 5 years) seed sensible mid-2026 example rates so you can quickly scan how a CD ladder rung might pay; replace the rate with the one your bank or credit union actually offers before relying on the number. An optional month-by-month projection table shows each month's interest, cumulative interest, and end-of-month balance, useful when you need to attribute interest to specific calendar months for tax planning or to compare against a savings account statement. A plain-text copy-summary button produces a clean block you can paste into a budget spreadsheet, a bank email, or a personal finance journal. Useful for savers comparing 1-year and 5-year CDs, retirees building a CD ladder for fixed-income predictability, anyone deciding whether to break a CD early for a higher rate elsewhere, students learning the difference between APY and APR, and shoppers running numbers across several banks before opening an account. All math runs locally in your browser. Nothing you enter, including deposit amounts, rates, or tax assumptions, is uploaded, logged, or sent to any server. The tool computes what you provide; it is not financial or tax advice and it does not check FDIC or NCUA insurance limits for you.

Free to use. Works in your browser. No signup, no login.