CD maturity calculator
Estimate a certificate of deposit at maturity.
- Formula and assumptions shown
- Table and CSV export
- Runs in your browser
How it works
A certificate of deposit is modeled here as one starting deposit that remains invested for a fixed term. Enter the APY that banks advertise, or switch the rate type to a nominal interest rate compounded at the frequency you choose. No recurring deposits are added.
With an APY: maturity = deposit × (1 + APY)^(months ÷ 12), and the rate per period is (1 + APY)^(1 ÷ periods per year) − 1. With a nominal rate: maturity = deposit × (1 + rate ÷ periods per year)^(periods per year × months ÷ 12).
The maturity estimate helps compare term and rate assumptions. Actual certificates can have renewal rules, early-withdrawal penalties, or taxes that are outside this model.
Assumptions
- The starting deposit is the only contribution.
- The rate is read as an APY unless you choose a nominal annual rate; either way it stays fixed until maturity.
- Interest remains in the certificate and compounds at the selected frequency. With an APY, the frequency does not change the result, because the APY already includes compounding.
- Early-withdrawal penalties, taxes, and renewal terms are not modeled.
Worked example
Worked examples on this page use US dollars.
$5,000 at 4% APY for one year
The maturity value is $5,000 × 1.04 = $5,200.00, including $200.00 of interest. If 4% is instead a nominal rate compounded monthly, the estimate is $5,000 × (1 + 0.04/12)^12 = about $5,203.71, including $203.71 of interest.
Step by step
- Start from the APY. A 4% APY means each dollar grows to 1.04 over a full year. The APY already includes compounding, which is why banks advertise it.
- Find the rate per compounding period. With monthly compounding, (1.04)^(1 ÷ 12) − 1 = 0.3274% per month (0.0032737 as a decimal), an equivalent nominal rate of 3.93%.
- Compound over the term. A 12-month term has 12 ÷ 12 × 12 = 12 monthly periods, and (1 + 0.0032737)^12 = 1.04: twelve monthly credits add back up to the APY.
- Apply it to the deposit. $5,000 × 1.04 = $5,200.00 maturity value.
- Subtract the deposit for interest. $5,200.00 − $5,000 = $200.00 of interest. If 4% were instead a nominal rate compounded monthly, choosing that rate type gives (1 + 0.04 ÷ 12)^12 = 1.040742, a $5,203.71 maturity value with $203.71 of interest, because a 4% nominal rate is a 4.0742% APY.
How to read your result
Maturity value is what the certificate is worth at the end of the term if the deposit and all credited interest stay in the account. Interest earned is maturity value minus the deposit, and Term repeats the months you entered. The last figure converts the rate to the other convention: the equivalent nominal rate when you enter an APY, or the APY when you enter a nominal rate. The bar chart and table show deposit, interest, and maturity value on one dollar scale.
Terms that are not whole years use a fraction of a year: an 18-month CD at a 4% APY grows by 1.04^1.5, so $5,000 becomes $5,302.98. Check which rate the bank quotes before entering it. The APY is the figure in CD advertisements; the interest rate, if shown, is the nominal rate before compounding and is slightly lower.
The estimate assumes the money stays in until maturity. It does not model early-withdrawal penalties, taxes on interest, interest paid out instead of compounded, or what happens at renewal, when many CDs roll into a new term at whatever rate applies then.
What changes the result most
- Term
- Doubling the term to 24 months at a 4% APY gives $5,408.00, which is $408.00 of interest, slightly more than twice the one-year $200.00 because the second year earns on the first year’s interest. A 60-month term reaches $6,083.26.
- Rate
- A 4.5% APY instead of 4% raises the one-year maturity value to $5,225.00, which is $25.00 more interest on $5,000.
- Compounding frequency
- With an APY it changes nothing: 4% APY on $5,000 for a year is $5,200.00 whether interest compounds daily or annually. With a 4% nominal rate it matters a little: daily compounding gives $5,204.04, monthly $5,203.71, and annual $5,200.00.
Questions
Can I add monthly deposits?
This tool treats the CD as a single fixed deposit. Use a savings or compound-growth calculator for recurring contributions.
Does the result include an early-withdrawal penalty?
No. This model has no penalty field. Check the certificate agreement because early-withdrawal terms vary by provider and account.
Is the entered rate an APY?
Yes, by default. US banks and credit unions advertise CDs by APY, which already includes compounding, so the compounding setting does not change the result. If you have the interest rate before compounding instead, set the rate type to nominal annual rate and choose how often it compounds.
Are CDs worth it?
It depends on what the money is for. A CD fixes the rate for the term, and deposits at FDIC-insured banks are insured up to $250,000 per depositor, per bank, per ownership category. In exchange, the money is committed until maturity, and taking it out early usually costs a penalty. Comparing the CD’s maturity value with a liquid savings account at its current rate, and with expected inflation, shows the trade-off in dollars.
How are CD early withdrawal penalties calculated?
The account agreement sets the penalty, and it is often stated as a number of days or months of interest. Federal Regulation D sets a minimum of seven days’ simple interest for money withdrawn within six days of deposit. As an illustration, a penalty of three months’ simple interest on $5,000 at 4% would be $5,000 × 0.04 × 3 ÷ 12 = $50.
Is CD interest taxable?
In the United States, interest on CDs and other bank deposits is generally taxable income. The IRS (Topic No. 403, Interest received) says payers issue Form 1099-INT when they pay $10 or more of interest. This calculator shows interest before any tax.
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Sources
These references explain the concepts behind the calculation. They do not endorse this site. Estimates leave out any cost or condition you did not enter.