See what any bank's CD rate is really worth.
Rate is quoted as
1 year
Common terms
Compounding frequency
$25,000.00 in a 1 year CD at 4.35% APY, compounded daily, grows to $26,087.50 — that’s $1,087.50 of interest, averaging $90.63 per month.
Balance over the term
| Month | Principal | Interest | Balance |
|---|---|---|---|
| At opening | $25,000.00 | $0.00 | $25,000.00 |
| 2mo | $25,000.00 | $178.05 | $25,178.05 |
| 5mo | $25,000.00 | $447.50 | $25,447.50 |
| 7mo | $25,000.00 | $628.74 | $25,628.74 |
| 10mo | $25,000.00 | $903.02 | $25,903.02 |
| 1y | $25,000.00 | $1,087.50 | $26,087.50 |
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 CD rate calculator turns a bank's advertised rate into the dollar figure you will actually hold at maturity, which is the only number worth comparing between offers. Enter the deposit, the quoted rate and the term, and the tool applies A = P(1 + r/n)^(nt). A $10,000 deposit at 4.50% APY for 12 months matures at $10,450.00. The reason a calculator beats reading the rate is that headline rates are not directly comparable: one bank may quote 4.50% APY while another quotes a 4.40% nominal rate compounded daily, and those are the same CD. Rates are also frequently tied to a minimum balance or a promotional term that reverts on renewal. Convert every offer to a maturity value on your own deposit and your own term, and the ranking often changes.
Formula & method
A = P(1 + r/n)^(nt)
The standard compound interest formula banks use to credit CD interest.
Convert the advertised rate to a decimal: divide the percentage by 100.
Divide that decimal by the number of compounding periods per year (n).
Add 1, then raise the result to the power of n × t.
Multiply by your principal. That product is your maturity value.
Subtract the principal to isolate the interest the rate earned you.
Guide
Type the amount you plan to place in the CD, or drag the slider. Check it clears the bank's minimum opening deposit.
Use the rate from the bank's rate sheet. Toggle APY or APR to match exactly how the bank quotes it — this matters.
Pick the term the rate applies to. Promotional rates are usually tied to one specific term such as 7 or 13 months.
Change the rate to a competing bank's offer and watch the maturity value update live. The gap is the real cost of choosing the lower rate.
Examples
Inputs
Result
A 0.35 percentage-point gap is worth $87.50 over one year on $25,000 — small in isolation, but it compounds every time you renew.
Methodology
The rate you enter stays fixed for the entire term, which is true of standard fixed-rate CDs.
Interest stays in the CD and compounds rather than being paid out to a linked account.
No additional deposits are made — most CDs do not permit them after opening.
Results are before tax. CD interest is taxable as ordinary income in the year it is credited.
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
APY already includes the effect of compounding; APR does not. Comparing an APY at one bank to an APR at another overstates the second bank's offer.
Rate sheets change weekly. Confirm the rate is still live and locked before you fund the account.
Promotional 'odd-term' CDs (7, 11, 13 months) often carry the best rates because banks use them to attract new deposits.
A rate is only guaranteed for the initial term — most CDs auto-renew at the bank's then-current standard rate, which is usually lower.
How it connects
Applications
You have offers open in three browser tabs and need the dollar difference, not the percentage difference.
Your CD is maturing and you want to know whether your bank's renewal rate is worth accepting.
You are parking a large balance and even a fractional rate gap moves real money.
Related tools
FAQs
You calculate a CD rate by applying A = P(1 + r/n)^(nt): P is your deposit, r is the annual rate as a decimal, n is how many times per year the bank compounds, and t is the term in years. A CD does not pay a flat percentage once — interest is credited at the interval in your disclosure, and each credited amount earns interest of its own for the rest of the term. Convert the rate to a decimal, divide by n, add 1, raise that to the power of n times t, and multiply by your deposit to reach the maturity value. On $10,000 at 4.50% APY compounded daily for 12 months, the formula returns $10,450.00, which is $450.00 in interest. If the quoted rate is already APY rather than nominal, set n to 1, because APY has already absorbed compounding and applying it again overstates the result.
Security & privacy
Uses the same compound interest and APY conventions as banks under Regulation DD.
No signup, no email wall, no paywall. Every calculator is fully usable on first visit.
Every calculation runs client-side in JavaScript. Nothing is sent to a server or stored.
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A quarter point sounds like nothing until you see it in dollars. Run your numbers through both offers before you commit your deposit.