CD calculator
Use the CD calculator to see what a certificate of deposit will be worth at maturity. Tweed's CD calculator is different because it shows the effective APY next to the rate your bank quoted, so you can compare CDs that compound at different frequencies without converting anything by hand.
12 or more rolls into a full year above
Enter 0 if this CD is held in a traditional or Roth IRA
Maturity value
$10,831.43
| Interest earned | $831.43 |
| Effective APY | 4.07% |
| Federal tax at 0.00% | $0.00 |
| Balance after tax | $10,831.43 |
Insured by the FDIC up to $250,000 per depositor, per bank, per ownership category.
| Year | Balance |
|---|---|
| 1 | $10,407.42 |
| 2 | $10,831.43 |
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Verified July 24, 2026Regulation DD (12 CFR Part 1030) and FDIC guidanceHow this is calculated
This calculator follows Regulation DD's APY formula exactly: APY = (1 + r/n)n − 1, where r is the nominal annual rate and n is the number of compounding periods per year.1 It does not model early-withdrawal penalties, promotional or step-up rates that change during the term, or state taxes on the interest.
In this article
How to use the CD calculator
Everything you need is in the account disclosure. Three inputs, then the numbers out.
1. Enter your deposit and the rate
The deposit is what goes in. Check whether your bank quotes APR or APY, since they're not the same number. If it already says APY, compounding is baked in.
2. Set the term and compounding frequency
Enter the term in years and months, and the compounding frequency stated in the disclosure. Daily and monthly are the two most common.
3. Add your tax rate to see what you keep
Use the top marginal rate your income reaches, not an average. CD interest stacks on top of everything else you earn. Set it to zero for a CD held inside an IRA.
How is CD interest calculated?
CD interest is calculated by compounding your deposit at a per-period rate for every period in the term.
- Start with your deposit, the principal P.
- Divide the annual rate by the number of compounding periods per year to get the per-period rate.
- Grow the balance by that per-period rate for every period across the term: A = P × (1 + r/n)^(n×t).
- Interest earned is the maturity value minus your deposit, A − P.
- The effective annual yield, APY = (1 + r/n)^n − 1, is the federally defined way to compare CDs that compound at different frequencies.1
APY by compounding frequency
Same $10,000, same 4.00% nominal rate, same two-year term. Only the compounding schedule changes.
| Compounding | Periods per year | Effective APY | $10,000 after 2 years |
|---|---|---|---|
| Daily | 365 | 4.08% | $10,832.82 |
| Monthly | 12 | 4.07% | $10,831.43 |
| Quarterly | 4 | 4.06% | $10,828.57 |
| Semi-annual | 2 | 4.04% | $10,824.32 |
| Annual | 1 | 4.00% | $10,816.00 |
Tweed calculations from the stated inputs. These are not quoted market rates.
Why APY matters more than the interest rate
Two CDs can quote the identical nominal rate and pay different amounts, because APY folds compounding in and the quoted rate does not.
Comparing APYs is the apples-to-apples comparison, and it is the number Regulation DD requires banks to disclose.1
A bank advertising a slightly lower rate with daily compounding can out-earn a competitor's higher rate compounded annually. The rate alone can't tell you that. The APY always can.
Run your own numbers
See your maturity value and APY in seconds
CD calculation example: $10,000 at 4.00% for two years
Start with a $10,000 deposit at a 4.00% nominal annual rate, compounding monthly, over a two-year term.
The periodic rate is 4.00% divided by 12, or 0.00333. Compounding across 24 monthly periods gives a maturity value of $10,831.43.
Subtract the deposit and the interest earned is $831.43. Converting the periodic rate to an annual yield gives an effective APY of 4.07%, higher than the 4.00% nominal rate because compounding is doing real work over two years.
Run your own deposit, rate, and term through the calculator above.
What happens if you withdraw early
Early-withdrawal penalties are set by the bank, not by federal rule, and are commonly quoted as a number of months of interest.
A penalty can exceed the interest earned on a short-held CD, which means you can get back less than you deposited.
The maturity figure above assumes you hold the CD to term. This calculator does not model early-withdrawal penalties, since they vary by institution and aren't centrally published. Check your own account disclosure for the specific terms.
Frequently asked questions about CD calculators
How much does a $10,000 CD earn in interest?
A $10,000 CD earns different amounts depending on the rate, term, and compounding frequency your bank offers. At a 4.00% nominal rate compounding monthly over two years, for example, it earns $831.43 in interest, ending at $10,831.43. Run your own numbers in the calculator above.
How is CD interest calculated?
CD interest is calculated by compounding your deposit at a per-period rate for every period in the term: divide the annual rate by the compounding frequency, then grow the balance by that rate each period. The maturity value minus your original deposit is the interest earned.
What is APY on a CD, and how is it different from the interest rate?
APY on a CD is the effective annual yield once compounding is factored in, while the interest rate is the raw nominal rate before compounding. APY is always equal to or higher than the stated rate, and it's the only number that lets you compare CDs with different compounding schedules.
Do CDs compound daily or monthly?
CD compounding frequency varies by bank and by product, with daily and monthly the two most common schedules. Check the account disclosure for the exact frequency, since a bank rarely states it prominently. If you can't find it, assuming monthly is the safer estimate, since it slightly understates rather than overstates.
Is CD interest taxed?
CD interest is taxed as ordinary income in the year it's credited to your account, even on a CD you can't touch without a penalty. Banks report interest over $10 to the IRS on Form 1099-INT, but smaller amounts are still taxable even without a form.
Is money in a CD FDIC insured?
Money in a CD is FDIC insured up to $250,000 per depositor, per bank, per ownership category, the same standard limit that covers savings and checking accounts. Credit union CDs carry equivalent NCUA coverage instead. Spreading larger balances across ownership categories or institutions extends the protection further.
Nicolas Straut
Personal finance writer, former Forbes contributor and This Week in Fintech writer