CD Calculator
CD Account Terms
CD Maturity Results
| Investment at Maturity | — |
|---|---|
| Total Interest Earned | — |
How to Use This CD Calculator
CDs advertise APY, lock you in for a term, and quietly tax the interest unless you're in a sheltered account. Before laddering three tranches, I run the maturity number here with tax and inflation toggles so I'm not comparing headline yield to real spending power.
- Enter deposit amount. Use the principal you plan to lock in for the full term.
- Enter APY. Banks quote Annual Percentage Yield—enter that figure, not a nominal rate.
- Set term in years and/or months. Match the CD maturity on the offer sheet.
- Choose compounding frequency. Select daily, monthly, or other schedule as stated in the CD disclosure.
- Add optional tax and inflation rates. Tax reduces after-tax interest; inflation shows real purchasing power at maturity.
- Press Calculate. Review maturity value, interest earned, after-tax value, and inflation-adjusted value.
Compare flexible savings without a lock-up using the Savings Calculator, or model bond-style fixed income with the Bond Calculator.
CD Formulas and Practical Applications
A certificate of deposit is a timed vault: you trade liquidity for a guaranteed rate. APY already embeds compounding, so the math starts by converting APY to a per-period rate, then growing the deposit through the term.
APY to periodic rate
rperiod = (1 + APY)1/n − 1
Maturity = Deposit × (1 + rperiod)n×t
A $10,000 CD at 4.8% APY compounded daily for 12 months matures near $10,491 before tax—about $491 interest if held to term.
After-tax and real value
Taxable CD interest is ordinary income in most cases. Entering a 24% tax rate on $491 interest leaves roughly $373 after tax. Layer 3% inflation and the real purchasing power of the maturity balance drops further—why APY alone doesn't tell the whole story.
Frequently Asked Questions
Should I enter APY or nominal rate for a CD?
Enter the APY quoted by the bank. The calculator converts APY to a periodic rate based on your selected compounding frequency.
How does the tax rate field work?
Optional tax rate reduces interest earnings for an after-tax maturity estimate. Tax-exempt accounts can leave this at zero.
What does the inflation field show?
Inflation adjusts the maturity value into approximate purchasing-power terms so you can compare CD growth to rising prices.
Does this model early withdrawal penalties?
No. Results assume the CD is held to full maturity with no partial withdrawals.
How does compounding frequency affect CD returns?
Given the same APY, more frequent compounding (daily vs annual) produces a slightly higher ending balance because interest accrues sooner.