See what twelve months in a CD actually earns.
Rate is quoted as
1 year
Common terms
Compounding frequency
$25,000.00 in a 1 year CD at 4.25% APY, compounded daily, grows to $26,062.50 — that’s $1,062.50 of interest, averaging $88.54 per month.
Balance over the term
| Month | Principal | Interest | Balance |
|---|---|---|---|
| At opening | $25,000.00 | $0.00 | $25,000.00 |
| 2mo | $25,000.00 | $174.03 | $25,174.03 |
| 5mo | $25,000.00 | $437.34 | $25,437.34 |
| 7mo | $25,000.00 | $614.41 | $25,614.41 |
| 10mo | $25,000.00 | $882.33 | $25,882.33 |
| 1y | $25,000.00 | $1,062.50 | $26,062.50 |
Calculated in your browser using A = P(1 + r/n)nt. Nothing is sent to a server. Figures are before tax; confirm exact terms with your bank.
Formulas and content last reviewed . Bank rates change frequently — confirm current rates directly with your institution.
The short answer
A 1-year CD is the reference term for the whole market — it is the one where the quoted APY and the return you actually receive are the same number. A $25,000 deposit at 4.25% APY earns exactly $1,062.50 and matures at $26,062.50; $10,000 earns $425.00, which is $35.42 a month if you take the interest as income. Because the term matches the annualisation period, no conversion is needed and comparison against any other saving option is direct. The thing that most often goes wrong with a 12-month CD is not the rate but the renewal: the term rolls automatically at the end of a 7-to-10-day grace period, at whatever the bank's standard 12-month rate is on that day. Savers who opened on a promotional rate and did nothing at maturity frequently find the second year paying a full percentage point less than the first.
Formula & method
A = P(1 + r/n)^(n), t = 1
At a one-year term the exponent collapses to n, and the APY is exactly the return you receive.
If the bank quoted an APY, multiply the deposit by (1 + APY) and you are finished.
If it quoted a nominal APR, divide by n and raise (1 + r/n) to the power n.
Multiply by the deposit for the maturity value.
Subtract the deposit for the year's interest.
Divide that by twelve for the monthly interest figure, if you plan to draw it.
Guide
Type the amount or drag the slider. Twelve-month CDs generally carry the lowest minimums on the sheet, often $500 or $1,000.
Set the toggle to APY if that is how the bank quoted it. On a one-year term an APY needs no conversion — the maturity value is simply deposit × (1 + APY).
Divide the year's interest by twelve if you intend to draw the interest rather than compound it. Drawing it lowers the maturity value.
Note the maturity date and the grace period before you open. That single step is worth more than a 0.10% better rate.
Examples
Inputs
Result
At a one-year term the APY and the realised return are identical — 4.25% quoted, 4.25% received. This is the only term where that is true, which is why the 12-month CD is the standard benchmark for comparing offers.
Inputs
Result
Missing the grace period cost $260.63 in a single year — more than a quarter of the first year's interest, and far more than any realistic difference between two banks' opening rates. Diarise the maturity date the day you open the CD.
Methodology
Interest is retained in the CD. Taking the monthly interest as income lowers the maturity value, because the withdrawn interest stops compounding.
The rate is fixed for the full twelve months, which is standard for a fixed-rate CD but not for a step-rate or bump-up product.
The renewal example uses an illustrative standard rate. Check your own bank's non-promotional 12-month rate — the gap is often wider than the one shown.
Figures are gross of tax. A full year of interest above $10 is reported to the IRS on Form 1099-INT.
Conventions follow Regulation DD (12 CFR 1030), which governs how US institutions disclose APY on deposit accounts. Deposits at insured institutions are FDIC-protected up to $250,000 per depositor, per bank, per ownership category.
Primary sources
Details
One year is the only term where APY and realised return coincide, which makes it the natural unit for comparing everything else. A 4.40% six-month CD and a 3.80% five-year CD are both quoted per year so they can be lined up against this one.
Auto-renewal is the default at nearly every institution. The grace period is typically 7 to 10 calendar days from maturity, and it is the only window in which you can move the money without a penalty.
Promotional 12-month rates almost never renew at the promotional rate. Treat the second year as unpriced until you see the sheet on the maturity date.
A 13-month or 15-month promotional CD is often priced above the standard 12-month term. If your horizon has any give in it, check the odd terms before defaulting to twelve.
Early withdrawal on a one-year CD is typically penalised at 90 days of interest. Breaking a $25,000 CD at 4.25% after six months costs $261.99 against $525.72 earned — you keep roughly half.
How it connects
Applications
Money for a car, a wedding or a tax bill twelve months out. The date is known, the rate is fixed, and the comparison against any alternative is direct because everything is quoted annually.
The 12-month rung is the backbone of most CD ladders. Once a five-rung ladder is mature, one rung comes due each year and gets reinvested at the longest term.
If a CD is coming due, this page prices the renewal against what you could get by moving. The grace period is short — knowing the number before it opens is what makes acting possible.
Related tools
FAQs
At 4.25% APY, exactly $1,062.50 — maturing at $26,062.50, or $88.54 a month if you draw the interest. On a one-year term the APY is the return, so no conversion is needed.
Security & privacy
Uses the same compound interest and APY conventions as banks under Regulation DD.
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See the interest, the monthly figure and what auto-renewal at a lower rate would cost you.