What is a CD?
A certificate of deposit (CD) is a savings account that pays a fixed interest rate for a fixed period, called the term. In return for the guaranteed rate, you agree to leave the money alone until the CD matures. Common terms run from three months to five years, and longer terms often pay higher rates.
How to use the CD calculator
- Enter the amount you plan to deposit.
- Enter the rate from your bank and choose whether it is an APY or an APR.
- Set the term in months or years.
- If you chose APR, pick how often interest compounds. Daily and monthly are the most common for CDs.
The calculator shows the value at maturity, the interest you will earn, and the effective APY. The table underneath compares the same rate across popular terms so you can see what a longer or shorter CD would pay.
APY vs. APR on a CD
APR (annual percentage rate) is the plain yearly interest rate. APY (annual percentage yield) is what you really earn in a year once compounding is included. Because banks are required to show APY on deposit accounts, it is the easiest number for comparing CDs from different banks.
For example, a 4.40% APR compounded daily works out to about a 4.498% APY. On $10,000 for a year that earns $449.80, almost the same as a CD advertised at 4.50% APY.
How CD interest is calculated
When you know the APY, the value at maturity is:
When you know the APR and the compounding frequency n, it is:
For a CD shorter or longer than a year, "years" is simply the term in months divided by 12.
Worked examples
- $10,000 in a 12-month CD at 4.50% APY grows to $10,450.00, earning $450.
- The same deposit in an 18-month CD at 4.50% APY grows to $10,682.54.
- $25,000 in a 5-year CD at 4.00% APY grows to $30,416.32.
Tips for choosing a CD
- Match the term to when you need the money. Early withdrawal penalties can wipe out months of interest.
- Consider a CD ladder. Split your savings across several CDs that mature at different times, for example 1, 2, 3, 4 and 5 years. One CD comes due every year, so part of your money is always within reach.
- Watch for automatic renewal. Put a reminder in your calendar a week before the maturity date so you can shop for a better rate.
- Compare APY, not APR. APY already accounts for compounding, so it gives a fair comparison between banks.
Last reviewed October 2026.