Free online tool
CD Interest and APY Calculator
Estimate certificate-of-deposit interest, maturity value, and effective annual percentage yield from a stated interest rate.
Certificates of deposit usually advertise annual percentage yield (APY), which reflects compounding over a year. Enter a nominal annual interest rate, compounding frequency, deposit, and term to compare the stated rate with its effective yield.
How to use it
- Enter the amount deposited into the CD.
- Enter the stated annual interest rate and the CD term in months.
- Choose the compounding frequency shown in the institution’s account disclosure.
Good to know
APY reflects the total interest produced by the stated annual interest rate and compounding frequency over a one-year period. More frequent compounding can make APY slightly higher than the nominal interest rate.
This estimate assumes the rate remains fixed, interest stays in the account until maturity, and there are no withdrawals, fees, taxes, penalties, bonuses, or special day-count rules. The institution’s disclosures control the actual result.
Behind the answer
How this calculator works
The maturity estimate uses compound interest: principal × (1 + annual rate ÷ compounding periods) raised to the number of compounding periods in the term. Estimated interest is maturity value minus principal.
APY expresses the effective one-year return after compounding. It can be slightly higher than the nominal interest rate when interest compounds more than once per year.
Worked example
A $10,000 deposit earning a 4.50% nominal rate compounded monthly for 12 months grows to approximately $10,459. The corresponding APY is about 4.59%, before taxes or fees.
Assumptions and limitations
- The estimate assumes a fixed rate and that all interest remains deposited.
- It excludes early-withdrawal penalties, taxes, fees, promotional rules, and institution-specific day-count methods.
- For terms shorter or longer than one year, APY is still an annualized comparison measure—not the actual percentage earned during the term.
Common questions
What is the difference between rate and APY?
The interest rate is the stated nominal rate. APY incorporates compounding and makes deposit products easier to compare on a one-year basis.
Is a CD automatically insured?
Coverage depends on the institution, ownership category, and deposit limits. Confirm that the bank is FDIC-insured or the credit union is federally insured before depositing.
Helpful sources
Sources reviewed October 2026.