CalculatopiaCertificate of Deposit CD Calculator
This certificate of deposit CD calculator turns your deposit, the CD's APY or nominal rate, and its term into the interest earned and the balance at maturity. It also works as a rate calculator for CD offers, so you can compare terms side by side.
How to use the CD calculator
- Enter the amount you plan to deposit in US dollars.
- Choose APY if the bank quotes an annual percentage yield, or nominal rate if it quotes an interest rate before compounding.
- Enter the term in whole months, from 1 to 120.
- If you chose a nominal rate, pick how often interest compounds. APY already includes compounding, so frequency does not change an APY result.
- Read the maturity value and total interest, then save the scenario to compare another term or rate.
CD earnings by term
The table applies one illustrative rate to common CD terms so you can see how term length changes total interest. It is calculated with the same formula as the tool above. Real CD rates differ by bank and by term, so enter the APY from each offer you compare.
| Term | Interest earned | Value at maturity |
|---|---|---|
| 3 months | $110.65 | $10,110.65 |
| 6 months | $222.52 | $10,222.52 |
| 12 months | $450.00 | $10,450.00 |
| 18 months | $682.54 | $10,682.54 |
| 24 months | $920.25 | $10,920.25 |
| 36 months | $1,411.66 | $11,411.66 |
| 60 months | $2,461.82 | $12,461.82 |
Compounding frequency and APY
When a bank quotes a nominal interest rate, more frequent compounding produces a slightly higher APY. The table shows the equivalent APY for an illustrative nominal rate. Under Truth in Savings rules, banks must disclose the APY, which already reflects compounding, so comparing APYs is the simplest way to compare CDs.
| Compounding | Equivalent APY |
|---|---|
| Annually | 5% |
| Semiannually | 5.0625% |
| Quarterly | 5.0945% |
| Monthly | 5.1162% |
| Daily (365/year) | 5.1267% |
How the CD estimate works
The calculator models a fixed-rate CD with interest reinvested until maturity. It estimates growth, not a bank-specific payment schedule or tax return.
Example: a one-year CD
A hypothetical $10,000 CD paying 4.5% APY for 12 months earns $450 before tax, for a maturity value of $10,450. If you apply an assumed 22% tax rate to that interest, the estimated tax is $99 and the after-tax interest is $351. Principal plus after-tax interest is $10,351.
This example assumes a fixed APY, no fees, no early withdrawal, and tax paid outside the CD. The rate is illustrative, not a current bank offer. The monthly schedule uses this calculator's model; a bank's crediting and day-count rules can differ. The tax estimate applies one assumed rate and is not a personalized tax calculation.
APY and nominal interest are different inputs
APY: balance = principal × (1 + APY)^(months / 12)
Enter percentages in the form; the formula uses decimals. With $10,000 at 5% APY for 12 months, the estimated balance is $10,500 and interest is $500. APY includes compounding, so it must not be compounded a second time.
CFPB: interest rate and APY definitionsUsing a nominal annual rate
Nominal: balance = principal × (1 + rate / n)^(n × months / 12)
Here n is the number of compounding periods per year. A 5% nominal rate compounded monthly is about 5.1162% APY. Fractional compounding periods use equivalent growth; real banks may apply different day counts and crediting rules. This is not a loan APR converter.
A transparent, simplified tax estimate
After-tax interest = interest × (1 − assumed tax rate)
At a 24% assumed tax rate, $500 interest leaves $380 after an estimated $120 tax. The model treats tax as paid outside the CD and keeps the before-tax compounding path unchanged. Interest can be taxable each year; account type, state taxes, deductions, and timing are not modeled.
IRS: interest income and tax timingCheck the actual deposit terms
Early withdrawal penalties and special CD features can change returns. FDIC coverage is generally $250,000 per depositor, per insured bank, per ownership category; not a separate limit for every CD. Confirm the bank, coverage, and product agreement before opening an account.
FDIC: deposit insurance coverageCommon questions
Does this show current bank rates?
No. Enter the APY or nominal rate from the offer you are considering. The 5% starting value is a calculation example, not a current offer or recommendation.
Can I add money or withdraw early?
This model assumes one initial deposit and no early withdrawals or fees. Add-on, variable-rate, brokered, and callable CDs may need a different model. Use the actual product agreement to assess those terms.
Why can the monthly table differ from a bank statement?
The table estimates accrued growth over equal month fractions. A bank may use exact dates, a different day-count basis, periodic interest payments, or different rounding. The final estimate is useful for comparison, not a promised payout.
What is the difference between APY and the interest rate on a CD?
The interest rate, or nominal rate, excludes compounding; APY includes it. A 5% nominal rate compounded monthly is about 5.12% APY. Use APY mode when the bank lists APY, and nominal mode with the right frequency when it lists a rate.
How much interest will a $10,000 CD earn?
It depends on the APY and term. At an illustrative 4.5% APY, $10,000 earns about $450 in 12 months before tax. Enter the actual APY and term, and check the bank's disclosure for fees and penalties.