CD Calculator
Calculate your certificate of deposit maturity value, interest earned, APY vs APR, and early withdrawal penalty. Results update instantly.
Monthly Interest Breakdown
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How to Use the CD Calculator
Enter your deposit amount, the APY offered by your bank, the term in months, and your compounding frequency. The calculator instantly shows your maturity value, total interest earned, the relationship between APY and APR, your effective annual rate, and a full month-by-month breakdown of how your balance grows.
What Is a Certificate of Deposit?
A certificate of deposit (CD) is one of the safest savings vehicles available. You deposit a lump sum with a bank or credit union for a fixed period — anywhere from a few months to five years. In exchange for committing your money, the institution pays you a guaranteed, fixed interest rate that is typically higher than a standard savings account. At maturity, you receive your original deposit plus all accrued interest.
CDs are insured by the FDIC (Federal Deposit Insurance Corporation) for bank CDs, or the NCUA for credit union CDs, up to $250,000 per depositor per institution. This makes them essentially risk-free for amounts under the insurance limit.
APY vs. APR: What Is the Difference?
The Annual Percentage Rate (APR) is the nominal interest rate — the base rate before the effects of compounding. If a CD pays 5% APR with monthly compounding, your monthly rate is 5% ÷ 12 = 0.4167%. The Annual Percentage Yield (APY) accounts for compounding and reflects what you actually earn over a full year. Banks are required by law (Regulation DD) to disclose APY, because it gives a more accurate picture of your true return.
For monthly compounding at 5% APR: APY = (1 + 0.05/12)12 − 1 = 5.116%. The more frequent the compounding, the higher the APY relative to APR. For daily compounding, the same 5% APR becomes an APY of 5.127%.
Compounding Frequency Explained
Compounding frequency determines how often earned interest is added back to your principal balance, where it begins earning interest itself. The four common frequencies are:
- Daily: Interest computes and compounds every day (365 times per year). Earns the most, but the difference vs. monthly is typically just a few dollars on a standard CD.
- Monthly: Interest compounds 12 times per year. The most common frequency for CDs and savings accounts.
- Quarterly: Interest compounds 4 times per year. Less common but still seen at some credit unions.
- Annually: Interest compounds once per year. For short-term CDs under 12 months, APY and APR are identical.
Early Withdrawal Penalties
Withdrawing from a CD before its maturity date triggers a penalty — almost universally measured in months of interest. Common penalty schedules are:
- 3 months of interest for CDs with terms up to 12 months
- 6 months of interest for 1-3 year CDs
- 12 months of interest for CDs longer than 3 years
Penalties are applied against earned interest first. If you haven't earned enough interest to cover the penalty, it is deducted from your principal — meaning you could receive back less than you deposited. This calculator shows you the net early-withdrawal value so you can make an informed decision.
CD Laddering Strategy
A CD ladder spreads your money across multiple CDs with staggered maturities — for example, 3-month, 6-month, 9-month, and 12-month CDs. As each rung matures, you reinvest at the current rate. Laddering gives you regular access to a portion of your funds, reduces interest-rate risk, and lets you capture rate increases over time without sacrificing all liquidity for the full term.
When Does a CD Make Sense?
A CD is a strong choice when you have cash you are confident you will not need for the term — for example, a down payment fund you are not deploying for 12 months, or an emergency fund you keep in a tiered structure. If rates are expected to fall, locking in today's rate via a longer-term CD can be strategically valuable. If rates are expected to rise, short-term CDs preserve your ability to reinvest at higher rates as each term matures.
How the Calculator Works
The maturity value formula uses compound interest: A = P × (1 + r/n)n×t, where P is principal, r is the APR (converted from APY), n is the compounding periods per year, and t is the term in years. The APR is back-calculated from the APY you enter using APR = n × ((1 + APY)1/n − 1), ensuring that regardless of compounding frequency, the effective annual yield always matches the APY you input.