What your CD result shows
The headline is what the bank hands back on the maturity date: your deposit plus every dollar of interest it earned. Because a CD is a fixed-rate, fixed-term contract, that figure is knowable the day you open the account — the reason a CD is the one savings product where a calculator gives a number rather than a projection.
Three of the figures beside it are the ones that change decisions. Interest after tax matters because CD interest is taxed the year the bank credits it, not the year you can touch it. Breaking it early prices the escape hatch before you need it. The national average line says whether your rate is genuinely competitive or merely available. Compared against the FDIC national average of 1.68% APY (Jul 20, 2026).
How to use this CD calculator
- Initial deposit — what goes in on day one. Check the minimum too; advertised rates often require $500 to $2,500 to qualify.
- APY — the annual percentage yield from the offer. APY already includes the compounding, so it is the only figure worth comparing between banks.
- Term in months — as written on the offer. Longer is not automatically better; see below.
- Early withdrawal penalty — from the disclosure, in months of interest. The result shows what that would cost on the balance you entered.
- Advanced — add your marginal tax rate to see what you keep, or enter a nominal rate and its compounding frequency if that is what your rate sheet quotes.
The schedule under the chart shows interest accruing month by month on terms up to two years, and year by year beyond that.
What is a CD?
A certificate of deposit is a deposit account that pays a fixed rate in exchange for leaving a fixed sum untouched for an agreed term. At the end of it — maturity — you get the deposit and the interest. Withdraw sooner and the bank charges a penalty.
That trade is the entire product. A high-yield savings account keeps your money reachable but can cut its rate whenever it likes; a CD cannot cut yours, and cannot be raided on impulse either. Deposits carry the same FDIC insurance as any bank account, up to $250,000 per depositor per bank per ownership category — so what you are being paid for is giving up access, not taking credit risk.
Two features follow from the fixed term and surprise people. Only one deposit is allowed, so a CD cannot be a savings habit — that is what a savings goal is for. And most CDs renew automatically at maturity, often into whatever rate the bank happens to be offering that week, so a maturity date is a diary entry rather than a formality.
How CD interest is calculated
Balance = deposit × (1 + APY)months ⁄ 12
Because APY is defined as the yield after a year of compounding, applying it directly and raising it to the fraction of a year the CD runs gives the exact maturity value — no compounding frequency required. That is why banks quote APY: it makes offers comparable however often the bank compounds.
If your paperwork quotes a nominal rate instead, the conversion is APY = (1 + r/n)n − 1, where n is the number of compounding periods a year. The advanced panel does it for you. The difference is small — on a 4% rate, daily compounding beats annual by roughly four hundredths of a point — which is why the rate deserves your attention and the frequency does not. The APY calculator converts either way.
What breaking a CD early costs
Every bank charges for early access, and almost every bank expresses the charge the same way: a set number of months of interest. Three months is common on a one-year CD, six on a five-year one — and it applies whether or not the CD has earned that much yet.
That last point is the trap. Break a one-year CD in month two with a three-month penalty and there is not three months of interest to forfeit, so the shortfall comes out of your deposit — you get back less than you put in. The result panel flags exactly that case. It is also why a long CD is worse than its rate suggests if there is any chance you need the money early.
Two ways round it. A CD ladder splits the money across several terms so something matures every few months, and a no-penalty CD trades a little yield for the right to walk away. Both beat guessing.
Which CD term makes sense
Longer terms usually pay more, but not always: when markets expect rates to fall, banks sometimes pay more for a six-month CD than a five-year one rather than commit to today's rate for half a decade. Check the offers instead of assuming the curve slopes up.
Match the term to the money instead of to the rate. Cash you might need this year does not belong in a CD at all; an emergency fund needs to be reachable. A known expense eighteen months out is a natural fit for an eighteen-month CD. Money you will not touch for a decade is probably being wasted in a CD — over that horizon, invested returns have historically outpaced deposit rates by a wide margin, at the price of volatility a CD does not have.
Tax on CD interest
Interest is ordinary income, taxed at your marginal rate in the year the bank credits it. On a multi-year CD that means owing tax annually on interest you cannot yet withdraw, and the bank will issue a 1099-INT for each year it credits more than $10. Set the tax field to your marginal rate to see what you keep: a 4% CD at a 24% rate nets closer to 3%.
The exception worth knowing: a CD held inside an IRA is not taxed annually — the wrapper defers it, or removes it entirely in a Roth. For retirement money, where the CD lives matters as much as what it pays.
What this calculator assumes
- The rate holds for the whole term, which for a fixed-rate CD it does. A bump-up or step-rate CD does not work this way.
- Interest stays in the CD until maturity. Some banks let you take interest as monthly income instead, which stops it compounding and lowers the total.
- No deposits after opening, matching how CDs work.
- Tax is not deducted from the headline. It is shown separately so the maturity figure matches what the bank tells you.
- Automatic renewal is not modelled. Nobody can source next year's rate, so we do not guess one.
These are planning estimates, not an offer. Confirm the APY, the minimum and the penalty in the bank's disclosure.
CD questions people ask
Is a CD better than a high-yield savings account?
It depends on whether you need the money. A CD locks its rate for the term, which wins when rates are falling; a savings account stays reachable but can cut its rate any time. Many savers hold both.
What happens when my CD matures?
The bank pays out deposit plus interest — but usually only if you tell it to. Most CDs roll over automatically into a new term at the current rate after a grace period of seven to ten days, which can silently lock your money into an uncompetitive rate.
Can I lose money in a CD?
Only by withdrawing early. If the penalty is larger than the interest earned so far, it comes out of your principal and you get back less than you deposited. Otherwise a CD at an FDIC-insured bank returns your deposit in full, up to the insurance limits.
Do CD rates follow the Federal Reserve?
Closely. Banks price deposits against short-term rates, so CD yields rise and fall with the federal funds rate, though with a lag and never in lockstep. That lag is the reason a CD can still look attractive for weeks after the Fed changes course.