CD APY Calculator
Determine the effective Annual Percentage Yield on your certificate of deposit and see how compounding frequency drives real returns.
Results
The CD APY Calculator converts a nominal interest rate into an effective Annual Percentage Yield (APY) based on the selected compounding frequency. The output shows the precise yield difference between the stated rate and the actual return after compound interest is applied.
Annual Percentage Yield Mechanics
The Annual Percentage Yield (APY) reflects the true annual return on a deposit after compounding. Federal regulation (Truth in Savings Act) requires all banks and credit unions to disclose APY so depositors can make accurate comparisons across institutions.
The APY Formula
The APY formula is APY = (1 + r/n)n − 1, where r is the nominal annual rate and n is the number of compounding periods per year. A CD with a 5.00% APR compounded daily (n=365) yields an APY of 5.1267%. The same 5.00% APR compounded annually (n=1) yields an APY of exactly 5.0000%, because there is no intra-year compounding to generate additional interest.
Effective Yield vs. Nominal Rate
The nominal rate (APR) does not account for compounding, while the effective yield (APY) does. Two banks advertising identical 5.00% rates can produce different returns depending on compounding frequency. Bank A compounding daily generates $512.67 per $10,000 per year. Bank B compounding quarterly generates $509.45. The $3.22 difference is entirely due to compounding frequency, not the stated rate.
Continuous Compounding
Continuous compounding is a theoretical model where interest compounds an infinite number of times per year, calculated using the formula A = Pert. The mathematical constant e (approximately 2.71828) drives the calculation. A $10,000 deposit at 5.00% for 1 year under continuous compounding yields $10,512.71 — only $0.04 more than daily compounding ($10,512.67). Continuous compounding represents the absolute ceiling of compound interest growth.
APY Comparison Across Frequencies
The difference between APR and APY widens as compounding frequency increases. Adjust the nominal rate below to see how each frequency produces a different effective APY.
APY Frequency Breakdown
Slide to change the nominal APR and observe the resulting APY for each compounding frequency.
Truth in Savings Act (TISA)
The Truth in Savings Act (TISA) requires all FDIC-insured institutions to disclose the Annual Percentage Yield (APY) on deposit accounts. This federal regulation, implemented by Regulation DD, standardizes how banks calculate and present yield information. Before TISA, banks could advertise nominal rates without disclosing compounding effects, making direct comparisons difficult for depositors.
Fixed APY vs. Variable APY
There are 2 APY structures for certificate of deposit accounts: fixed and variable. Fixed APY locks the rate for the entire term, protecting the depositor from rate decreases. Variable APY fluctuates with market conditions, which benefits the depositor when rates rise but creates uncertainty. Standard CDs use fixed APY. Variable-rate CDs, Bump-Up CDs, and Step-Up CDs use adjustable APY structures.
Calculate Your CD APY
Enter your deposit parameters above to compute the effective Annual Percentage Yield and total compounding benefit on your certificate of deposit.
Calculate APYFAQs
What does APY mean on a CD?
APY on a CD means the Annual Percentage Yield, which represents the total effective return earned on the deposit over one year after accounting for compounding. APY is always equal to or greater than the stated APR.
How is CD APY different from the stated interest rate?
CD APY includes the effect of compounding, while the stated interest rate (APR) is the nominal rate before compounding is applied. A 5.00% APR compounded daily yields an APY of 5.1267%.
What is continuous compounding on a CD?
Continuous compounding is a theoretical model where interest compounds an infinite number of times per year. The formula A = Pert uses the mathematical constant e (≈2.71828). It represents the maximum possible yield for any given interest rate.
Why do online banks offer higher CD APY rates?
Online banks offer higher CD APY rates because they operate without physical branch networks, reducing overhead costs. These operational savings are passed to depositors through higher Annual Percentage Yields on certificates of deposit.
Can CD APY change after I open the account?
No, the APY on a standard fixed-rate CD cannot change after the account is opened. The rate is locked for the entire term. Variable-rate CDs, Bump-Up CDs, and Step-Up CDs are exceptions that allow rate adjustments during the term.