CD Calculator
Enter your deposit, pick a term, type the APY from the bank's offer — and see the maturity value and interest instantly. Know only the rate? Switch modes and we'll derive the APY.
Interest is taxable as ordinary income · early withdrawal usually costs months of interest · nothing you enter leaves this browser.
Spotted a mistake or have an idea? — errors get fixed and credited publicly.
Last reviewed: July 20, 2026 · Formulas verified by automated tests before every release.
How much interest will my CD earn?
Maturity value = deposit × (1 + APY)^years — APY already includes compounding, which is exactly why banks must advertise it. $10,000 at 4.5% APY becomes $10,450 in one year, $11,412 in three. Enter your own numbers above; if you only know the nominal rate, the rate-plus-compounding mode derives the true APY.
APY vs rate: the only CD trap that matters
Two banks offer "4.5%". One means 4.5% APY; the other means a 4.5% nominal rate compounded daily — which is really 4.60% APY. On $50,000 over three years that quiet difference is about $160. US truth-in-savings rules force banks to state the APY precisely so you can compare honestly: when choosing between CDs, compare APY to APY and ignore everything else in the fine print except the early-withdrawal penalty.
The early-withdrawal math nobody reads
A CD's rate is the rent the bank pays for locking your money. Break the lock and the penalty — commonly three to twelve months of interest — can erase a year of earning. If there's any chance you'll need the cash, the honest alternatives are a shorter term, a no-penalty CD at a slightly lower APY, or a ladder: splitting the money across staggered terms so a rung matures regularly. And if you're comparing a CD against simply investing the money, run the same numbers through the compound interest calculator — same formula, different risk story. Saving toward a specific goal instead? The savings goal calculator works backwards from the target.
Sources, assumptions and limitations
- Assumptions: APY mode: maturity = deposit × (1 + APY)^years — compounding is inside the APY by definition.Rate mode converts nominal rate to APY at your chosen compounding frequency.Interest shown is pre-tax; CD interest is ordinary income (1099-INT).Early-withdrawal penalties are not modelled — see the section above for how they typically work.Nothing you enter is stored or transmitted.
- Sources: ·
- Last reviewed: by the CalcNotebook team
Frequently asked questions
How much will a $10,000 CD earn in a year?
At 4.5% APY, $10,000 grows to $10,450 — $450 in interest. At 5% APY it earns $500. APY already includes compounding, so maturity = deposit × (1 + APY)^years. Use the calculator above for your exact numbers and term.
What's the difference between APY and interest rate on a CD?
The interest rate (APR) is the nominal annual rate before compounding; APY is what you actually earn after compounding is applied. A 4.4% rate compounded daily is about 4.50% APY. Banks must advertise APY precisely so you can compare apples to apples — when in doubt, use the APY.
What happens if I withdraw a CD early?
You typically forfeit a chunk of interest — commonly 3 months' worth on short CDs and 6–12 months' on longer terms (terms vary by bank; some charge even if interest earned is less than the penalty). If you might need the money, consider a shorter term, a no-penalty CD, or a CD ladder.
Are CDs insured?
Yes — CDs at FDIC-member banks are insured up to $250,000 per depositor, per bank, per ownership category (NCUA provides the same for credit union share certificates). The insurance covers principal and accrued interest within the limit.
Is CD interest taxable?
Yes — interest is taxed as ordinary income in the year it's credited, even if you don't withdraw it. The bank sends a 1099-INT for interest of $10 or more. This calculator shows pre-tax figures.
Do you store what I enter?
No. Amounts, rates and results exist only in this browser tab — nothing is uploaded or saved.