Money
CD Calculator
Enter your initial deposit, the APY, and the term length. The calculator returns the value at maturity, the interest earned, and an optional early withdrawal penalty estimate if you tell it how many months of interest the penalty represents.
The amount you put into the CD. · e.g. 10,000
Annual percentage yield as quoted by the bank. · e.g. 4.5
e.g. 12
Compounding frequency (display only)
APY already reflects compounding, so the maturity math does not change with this setting. Use it to see the implied nominal rate at each compounding choice.
Months of interest the bank deducts if you break the CD early. · e.g. 0
Value after 1 year
$10,450.00
Initial deposit $10,000.00 · interest earned $450.00
Estimate only. Real CDs can have minimum deposits, tiered APYs, callable features, and early withdrawal terms set by the bank.
Examples
$10,000 · 4.5% APY · 12 months
Maturity $10,450 · interest $450
$10,000 · 4.5% APY · 36 months
Maturity ≈ $11,411.66 · interest ≈ $1,411.66
$25,000 · 5.0% APY · 60 months
Maturity ≈ $31,907.04 · interest ≈ $6,907.04
$10,000 · 4.5% APY · 12 mo · 6-mo penalty
Maturity $10,450 · penalty ≈ $222.52 · net ≈ $10,227.48
How it works
A CD is a fixed-term, fixed-rate savings product. Because the bank quotes the rate as an APY, the math is the standard compound interest formula applied directly with APY as the effective annual rate.
Value at maturity
A = P × (1 + APY)^t
The parts
- A = value at maturity
- P = initial deposit
- APY = annual percentage yield (decimal)
- t = term in years
Interest earned
interest = A − P
Early withdrawal penalty estimate
penalty ≈ P × ((1 + APY)^(months ÷ 12) − 1)
APY already reflects compounding, so the calculator does not multiply by a compounding factor again. The implied nominal rate at each compounding choice is shown in the breakdown for context, but it does not change the maturity value.
What this calculator does
The CD calculator takes the three numbers the bank quotes (your initial deposit, the APY, and the term length) and returns the value of the CD at maturity, how much of that is interest, and an optional estimate of the early withdrawal penalty if you break the CD before maturity.
How the math works
Because APY is the effective annual rate, the future value of a CD is simply the initial deposit grown by (1 + APY) raised to the term in years. This avoids the double counting that can happen when a nominal rate is used along with a compounding factor.
If you have only a nominal rate, use the APY calculator to convert to APY first, then plug the APY into this CD calculator.
Term length
Common CD terms run from 3 months to 5 years, though longer terms exist. Enter the term in months or years using the unit toggle. The math is the same; the unit toggle just controls how you type the number.
Early withdrawal penalty
Banks charge a penalty if you break a CD before its term ends. The penalty is most often stated as a number of months of interest. The calculator translates that into a dollar value using your APY: penalty = principal × ((1 + APY)^(months ÷ 12) − 1). The net-if-broken-early line is the maturity value minus that penalty.
Real bank penalty rules can differ. Some compute the penalty on a daily-equivalent rate; some compute it only on interest already accrued; some have tiered penalty tables based on the term. Treat the calculator's penalty as a planning estimate.
Worked example
Initial deposit $10,000, APY 4.5%, term 12 months, no early withdrawal penalty.
- Term in years: 12 ÷ 12 = 1
- Value at maturity: 10,000 × (1 + 0.045)^1 = $10,450.00
- Interest earned: 10,450 − 10,000 = $450.00
If you broke the CD early with a 6-month interest penalty, the calculator estimates the penalty as 10,000 × ((1 + 0.045)^(6 ÷ 12) − 1) ≈ $222.52, which would leave about $10,227.48 net. The calculator shows that line whenever the penalty input is greater than zero.
CD vs other savings options
A CD locks in a rate for a fixed term, which is useful when rates are high and you can spare the principal for the full term. A high-yield savings account keeps the flexibility but has a variable rate. A money market account is in between. The right choice depends on your time horizon and how much liquidity you need.
For longer-term retirement money, see the 401k calculator and Roth IRA calculator. For modeling broader compounding scenarios with monthly contributions, use the compound interest calculator.
Common mistakes
- Treating APY as a nominal rate and adding compounding on top. APY already includes compounding.
- Comparing two CDs at the same nominal rate but different compounding. Convert both to APY first.
- Ignoring the early withdrawal penalty. If your goal might need the cash early, model the penalty so the effective return is realistic.
- Forgetting taxes. CD interest is generally taxable as ordinary income.
- Assuming a CD will roll over at the same rate. At maturity, the bank may offer a different APY or roll into a different product.
Related tools
- APY calculator for converting a nominal rate plus compounding into APY.
- Compound interest calculator for projecting balances with optional monthly contributions.
- 401k calculator for employer-sponsored retirement projections with salary growth and employer match.
- Roth IRA calculator for an individual after-tax retirement account.
Disclaimer. This calculator is an estimate for general planning. Actual CD terms, APYs, minimum deposits, early withdrawal penalties, renewal rules, and tax treatment can vary by bank and product. It is not investment, tax, or financial advice, and it does not guarantee any return.
Frequently asked questions
A CD is a savings product that locks a deposit in for a fixed term in exchange for a fixed interest rate. You agree not to touch the money until the term ends; the bank pays the quoted APY over that term. Most CDs come with an early withdrawal penalty if you break the term early.
Once you have the APY, the math is straightforward: value at maturity = initial deposit × (1 + APY)^(years). The APY already includes the compounding effect, so the formula does not multiply by compounding frequency again. For a 12-month CD, term in years is 1; for a 60-month CD, it is 5.
Banks advertise CDs in APY because APY is the honest one-year comparison number. Two CDs at the same APY pay the same interest for the same term, regardless of how often they compound. If you only have a nominal rate, convert it to APY first (or use the APY calculator) and then plug it in here.
It is display-only when the rate input is APY. APY already includes compounding, so the maturity value does not change with this setting. The calculator uses the frequency to back out the implied nominal interest rate at that frequency, which is useful if you want to compare to nominal-rate quotes.
Most CDs charge a penalty if you break the term early. The penalty is usually stated as a number of months of interest. The calculator estimates the penalty as initial deposit × ((1 + APY)^(penalty months ÷ 12) − 1), which gives the dollar value of that many months of interest at the CD's APY. Real penalty rules vary by bank.
It is a planning estimate. Banks calculate the penalty using their own rule, which may use a simple monthly interest amount, a daily-equivalent rate, or another formula. The penalty in this calculator is the same dollar value the bank's published months-of-interest rule would imply at the quoted APY, but the exact figure can differ.
A CD has a fixed term and a fixed rate, and it usually pays more than a regular savings account in exchange for the lock-in. A standard savings account has a variable rate, no lock-in, and lets you withdraw anytime. CDs are typically a fit when you have a chunk of money you do not need for a known period.
The interest rate on a CD is contractually fixed for the term, and CDs at FDIC-insured banks (or NCUA-insured credit unions) are insured up to the applicable limit. That is different from saying the calculator guarantees the result: the maturity value depends on the bank actually paying the contracted APY through to maturity.
The math is the same compounding family. A CD calculator is the simplest case: a one-time deposit, a fixed rate, a fixed term, and no recurring contributions. A savings or compound interest calculator usually adds monthly contributions and a longer time horizon. Use the right tool for your scenario.
No. CD interest is generally taxable as ordinary income in the year it is earned. The calculator returns pre-tax amounts. Your actual after-tax return will be lower based on your tax bracket and any state taxes.
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