🏦 Certificate of Deposit (CD) Calculator
Calculate certificate of deposit maturity earnings, APY compounding interest (daily, monthly, annually), and total interest payout. 100% free.
APY already includes compounding, so the maturity value is 5.25% compounded once a year no matter which frequency you pick. What the frequency changes is the posted nominal rate a bank must pay to yield that APY: 5.128% monthly.
What Certificate of Deposit (CD) Calculator Does
A certificate of deposit pays a fixed rate for a fixed term in exchange for leaving the money alone. This calculator takes a deposit, an APY and a term in months and returns the balance at maturity, the interest earned, and the nominal rate that corresponds to your APY at the compounding frequency you select.
APY is the number that matters, and it is worth being precise about why. Annual percentage yield is defined in federal regulation as the effective annual rate — the total percentage the balance grows in a year with compounding already included. That is what makes it comparable: a 4.00% APY at one bank beats a 3.95% APY at another regardless of how often either compounds, which is exactly the point of requiring banks to advertise it.
It also means compounding frequency cannot change what an APY earns you. This is a trap worth naming, because this calculator used to fall into it: it grew the APY as if it were a nominal rate, at (1 + APY ÷ n) raised to n·t. On $10,000 at 5.25% that overstated a one-year CD by $12.82 and a five-year CD by $78.84, and it made the compounding dropdown move a figure that mathematically cannot depend on it. The maturity value below is now (1 + APY) raised to the term in years, and the frequency selector drives the one thing it legitimately determines — the posted nominal rate.
How to Use Certificate of Deposit (CD) Calculator
- Enter your initial CD deposit amount
- Input the annual percentage yield (APY %)
- Select a CD term length (6, 12, 18, 24, 36, or 60 months)
- Choose compounding frequency (daily, monthly, or annual)
- Review your total balance at maturity and guaranteed interest profit
Formula Used by Certificate of Deposit (CD) Calculator
Maturity value from an APY
A = P × (1 + APY)^(months ÷ 12)
- P
- Initial deposit
- APY
- Annual percentage yield as a decimal — 5.25% is 0.0525
- months ÷ 12
- Term in years; a 6-month CD is an exponent of 0.5
- A
- Balance at maturity, principal plus interest
Worked example
$10,000 at 5.25% APY for 12 months, and the same deposit for 60 months.
- 12 months: 10,000 × 1.0525^1 = 10,525.00
- 60 months: 10,000 × 1.0525^5 = 12,915.48
- For comparison, the old incorrect method at monthly compounding gave 10,537.82 and 12,994.32
Result: $10,525.00 and $12,915.48. Because the rate is an APY, both figures are identical whichever compounding frequency is selected — that is what "effective" means.
The nominal rate behind an APY
nominal = n × [ (1 + APY)^(1 ÷ n) − 1 ]
- n
- Compounding periods per year: 365 daily, 12 monthly, 4 quarterly, 1 annually
- nominal
- The periodic rate annualized — the "interest rate" on the rate sheet, as opposed to the APY in the advertisement
Worked example
A bank advertises 5.25% APY and compounds monthly. What rate is it actually posting?
- (1 + 0.0525)^(1÷12) = 1.0042731
- 1.0042731 − 1 = 0.0042731 per month
- 0.0042731 × 12 = 0.051278
Result: 5.128% nominal. Daily compounding would be 5.117%, quarterly 5.150%. The more often it compounds, the lower the posted rate needed to reach the same advertised yield — which is why comparing posted rates across banks without converting them is comparing nothing.
The reverse: what a posted rate yields
APY = (1 + nominal ÷ n)^n − 1
- nominal ÷ n
- The rate actually applied each period
Worked example
Two banks both post 5.00%. One compounds daily, the other annually.
- Daily: (1 + 0.05 ÷ 365)^365 − 1 = 0.051267
- Annually: (1 + 0.05 ÷ 1)^1 − 1 = 0.050000
Result: 5.1267% APY against 5.0000% APY. On $10,000 for a year that is a difference of $12.67 — small, real, and completely invisible if you compare the posted rates alone. This is the reason Regulation DD requires the APY to be disclosed.
FDIC National Average CD Rates — as of 17 August 2026
The FDIC publishes these monthly, weighted by each institution's share of domestic deposits across all insured banks and credit unions. This is the benchmark to judge an offered rate against. The cap column is the ceiling a less-than-well-capitalized institution may pay.
| Term | National average rate | National rate cap | Interest on $10,000 at the average |
|---|---|---|---|
| 1 month CD | 0.22% | 0.97% | $1.83 |
| 3 month CD | 1.14% | 1.89% | $28.38 |
| 6 month CD | 1.41% | 2.16% | $70.25 |
| 12 month CD | 1.71% | 2.46% | $171.00 |
| 24 month CD | 1.57% | 2.32% | $316.46 |
| 36 month CD | 1.34% | 2.09% | $407.41 |
| 60 month CD | 1.36% | 2.11% | $698.75 |
How Much Will $10,000 Make in a 6-Month CD?
This is the question people arrive with most often. Computed as 10,000 × (1 + APY)^0.5, since six months is half a year.
| APY | Balance at maturity | Interest earned |
|---|---|---|
| 1.41% (national average) | $10,070.25 | $70.25 |
| 3.00% | $10,148.89 | $148.89 |
| 4.00% | $10,198.04 | $198.04 |
| 4.50% | $10,222.52 | $222.52 |
| 5.00% | $10,246.95 | $246.95 |
Is a 4% CD Good Right Now? $10,000 at 4.00% Against the National Average
The other question that comes up constantly. Judged against the FDIC averages above, a 4.00% APY is roughly double to triple the national average at every term — so yes, materially above market as of August 2026.
| Term | At the national average | At 4.00% APY | Difference |
|---|---|---|---|
| 3 months | $10,028.38 | $10,098.53 | +$70.16 |
| 6 months | $10,070.25 | $10,198.04 | +$127.79 |
| 12 months | $10,171.00 | $10,400.00 | +$229.00 |
| 24 months | $10,316.46 | $10,816.00 | +$499.54 |
| 36 months | $10,407.41 | $11,248.64 | +$841.23 |
| 60 months | $10,698.75 | $12,166.53 | +$1,467.78 |
Same APY, Different Posted Rate
What the bank must post at each compounding frequency to advertise the APY on the left. Computed as n × [(1 + APY)^(1/n) − 1].
| Advertised APY | Daily (n=365) | Monthly (n=12) | Quarterly (n=4) |
|---|---|---|---|
| 1.71% | 1.696% | 1.697% | 1.699% |
| 3.00% | 2.956% | 2.960% | 2.967% |
| 4.00% | 3.922% | 3.928% | 3.941% |
| 5.00% | 4.879% | 4.889% | 4.909% |
| 5.25% | 5.117% | 5.128% | 5.150% |
How to Read Your Result
A rate is only good relative to the market, and the market is published
The FDIC table above is the answer to "is this a good rate", and it is free federal data updated on the third Monday of every month. As of August 2026 the national average 12-month CD pays 1.71%, so a 4.00% offer is not a slightly better deal — it is more than double the average, $229 more on $10,000 over a year. Note also the shape of the curve: the average 12-month CD pays more than the average 60-month one (1.71% against 1.36%). Locking up money for five years is currently being paid less than locking it up for one, which is the opposite of the usual assumption that longer always pays more.
Compounding frequency is marketing, once you have the APY
Banks advertise daily compounding as a feature. It is real, but it is already inside the APY — that is the entire purpose of the disclosure. If two CDs both say 4.00% APY, one compounding daily and one annually, they pay exactly the same at maturity. The frequency only matters when you are comparing posted nominal rates, which is why this calculator shows the nominal rate corresponding to your APY rather than letting the dropdown change your maturity value.
What this does not price: breaking the CD early
The rate assumes the money stays put for the full term. Withdraw early and the bank charges a penalty, commonly quoted as a number of months of interest, and on short terms that penalty can exceed the interest earned — leaving you with less than you deposited. This calculator has no penalty input, so every figure on the page is a hold-to-maturity figure. Check the specific penalty in the disclosure before choosing a term, because the penalty, not the rate, is what makes a long CD risky.
Interest is taxable in the year it is credited
CD interest is ordinary income for federal tax purposes, reported on a 1099-INT, and it is taxed as it is credited — not when the CD matures. On a multi-year CD that means owing tax on interest you cannot yet withdraw without penalty. This calculator returns pre-tax figures only; Calculator.net offers a marginal tax rate input and this tool does not, so if the after-tax number is what you need, use theirs or apply your own bracket to the interest column.
Limitations & Accuracy Notes
- Pre-tax only. There is no marginal tax rate input, and CD interest is ordinary income taxed in the year it is credited.
- No early withdrawal penalty modeling. Every figure assumes the CD is held to maturity.
- Single deposit only. CDs generally do not accept additional contributions, so there is no recurring deposit input — but that also means this cannot model a CD ladder, where several CDs of staggered terms are run together.
- Fixed rate only. Bump-up, step-up, callable and index-linked CDs have rates that change during the term and cannot be represented by a single APY.
- No comparison of multiple offers side by side. To compare, run the calculation once per offer.
- The FDIC national averages quoted here are from the 17 August 2026 publication. They are updated on the third Monday of each month, so check the source before relying on the comparison.
- This does not tell you whether a CD is the right instrument. A rate above the national average can still lose to inflation, and money needed sooner than the term should not be in a CD at all.
Frequently Asked Questions
What is a Certificate of Deposit (CD)?
How does compounding frequency affect CD returns?
What is the difference between APY and the interest rate?
What happens if I withdraw early?
Are CDs insured?
What is a CD ladder?
Is a CD better than a high-yield savings account?
Is the interest taxable?
References & Further Reading
- FDIC — National Rates and Rate Caps — Source of every national average and rate cap in the table above, published monthly and weighted by each institution's share of domestic deposits. Figures used here are the 17 August 2026 release
- Regulation DD (Truth in Savings), 12 CFR Part 1030 — Defines annual percentage yield and requires it to be disclosed; Appendix A gives the APY formula that makes offers comparable across compounding frequencies
- FDIC — Deposit Insurance — The $250,000 per depositor, per insured bank, per ownership category limit that applies to CDs at insured banks