Find the principal amount
Find the annual interest rate
Convert the annual rate to a decimal
Determine the term of the CD in years
Use the simple interest formula: Interest = Principal × Rate × Time
If the CD compounds, use the compound interest formula: A = P(1 + r/n)^(nt)
Subtract the principal from the final amount to get the interest earned
Check whether the CD compounds daily, monthly, quarterly, or annually
Use the number of compounding periods per year in the formula
Verify whether the rate is APY or APR
Use the APY if you want the total return after compounding
Multiply the principal by the APY to estimate total earnings over one year
Adjust for early withdrawal penalties if the CD is cashed out early