A certificate of deposit trades access for a known rate. This calculator shows what that trade pays: the maturity value of your deposit, the total interest, how the balance grows month by month, and what the same money would have earned sitting in a regular savings account instead.
A CD is a loan you make to a bank for a fixed length of time at a fixed rate. You hand over the deposit on day one, the bank pays a stated APY, and the money comes back with interest at maturity. The rate does not move when the Federal Reserve cuts, and it does not move when the bank's own promotions change. That certainty is the entire product. You are paid for giving up access, and the early withdrawal penalty is the price of taking the access back early.
The certainty cuts both ways. Inflation is not fixed, and neither is the rate you could earn on the next deposit. A CD that looks generous today can look thin in three years if rates rise, which is one reason long terms rarely pay enough extra to justify the wait.
The Federal Deposit Insurance Corporation publishes national deposit rates every month, weighted by each institution's share of domestic deposits. In the table dated August 17, 2026, the national average savings account paid 0.38 percent, the average 12-month CD paid 1.71 percent, and the average 60-month CD paid 1.36 percent. The averages are dragged down by the largest banks, which hold most of the deposits and pay the least for them.
Two lessons sit in that table. First, the gap between products is enormous: on $10,000, a year in the average savings account earns $38 while a year in the average 12-month CD earns $171. Second, longer does not mean better. The average curve peaks at 12 months and declines after, so a saver who commits for five years has historically been paid less than one who commits for one. Rate averages describe what banks pay, and advertised offers from online banks routinely run well above them, which is why the default APY in this calculator is set at a competitive 4.00 percent rather than the national average.
Variables in plain terms. APY is the annual percentage yield the bank advertises, and it already includes the effect of compounding, which is why the calculator converts it to an equivalent monthly rate instead of dividing by twelve. Term is the lock-up length in months. Monthly addition applies only to add-on CDs that accept deposits after opening; most CDs do not. Savings APY is the rate your money would earn somewhere flexible, used here to price what the CD's lock-up actually costs you in flexibility.
Deposit $10,000 in a 12-month CD at 4.00% APY. The equivalent monthly rate is 0.327374%, so the first month earns $32.74 and the balance compounds from there. At maturity the CD is worth $10,400.00, of which $400.00 is interest. The same $10,000 left in a savings account at the FDIC national average of 0.38% earns $38.00 over the same year, so choosing the CD over the average account is worth $362.00.
Term changes the picture faster than rate does. The table below holds the deposit and APY fixed and varies the lock-up.
| Term | Maturity value | Interest earned |
|---|---|---|
| 6 months | $10,198.04 | $198.04 |
| 12 months | $10,400.00 | $400.00 |
| 24 months | $10,816.00 | $816.00 |
| 36 months | $11,248.64 | $1,248.64 |
| 60 months | $12,166.53 | $2,166.53 |
Compounding is doing quiet work in that table. Five years at 4.00% earns 21.7 percent of the deposit, more than five times the simple 20 percent that five single years without compounding would suggest. The trade is that the full $2,166.53 only arrives if the money stays put through every one of those 60 months.
Banks quote early withdrawal penalties as days of interest, and the schedules vary widely between institutions. On a $10,000 CD at 4.00%, 60 days of interest is $65.75, 90 days is $98.63, and 180 days is $197.26. Break a five-year CD under a 150-day penalty schedule in month three and the penalty wipes out nearly everything the deposit has earned, and can reach into principal. Regulation DD forces the bank to disclose the penalty before you open the account, so read that number before comparing APYs, because a 0.10 percent better rate is meaningless against a penalty schedule twice as long.
The standard defense is a CD ladder. Instead of one $10,000 five-year CD, open four CDs of $2,500 at 6, 12, 24, and 36 months. One tranche always matures within a year, which converts the penalty question into a planning question, and each maturing tranche can be re-deployed at whatever the current rate happens to be.
CDs earn their place on money with a known deadline and no better job: the house down payment that is two years out, the car replacement fund, the portion of an emergency fund beyond the first month of expenses. Money you are still actively building belongs somewhere flexible, and the savings goal calculator works out the monthly deposit that reaches a target by a date. The engine underneath a CD is ordinary compounding, and the compound interest calculator runs the same math over decades rather than months, which is the right view for retirement money. And since a CD's fixed rate is a bet against inflation, the inflation calculator shows what your maturity value will actually buy when the term ends, which is the honest test of whether the deposit won.
The interest rate is the nominal annual rate the bank pays. The APY is what you actually earn after compounding is folded in. A CD paying 3.92 percent compounded daily has an APY of 4.00 percent, and the APY is the only number you need for comparing offers, because it already answers the question of what the deposit grows to in a year. This calculator works directly from APY for that reason.
Yes. CD interest is taxed as ordinary income in the year the bank credits it, even if the CD has not matured. Banks report interest of $10 or more on Form 1099-INT, and for CDs maturing beyond a year they report the accrued interest each year. A 4 percent CD in the 22 percent federal bracket really nets about 3.1 percent after tax, which is the honest number to compare against municipal alternatives.
You pay an early withdrawal penalty, typically quoted as a number of days of interest. Regulation DD requires the bank to disclose the penalty before you open the account. The range is wide: a common schedule takes 60 days of interest on terms up to a year and 150 days or more on five-year CDs. On a $10,000 CD at 4 percent, that is roughly $66 for a 60-day penalty and about $164 for a 150-day one, and a penalty can reach into principal if you break the CD very early.
It depends entirely on the APY. At the FDIC national average of 1.71 percent for a 12-month CD, $10,000 earns $171 in a year. At the roughly 4 percent APY that leading online banks have offered on the same term, it earns $400. The deposit is identical; shopping for the rate is worth more than any other decision in the process.
Usually not. Most CDs accept a single deposit at opening and nothing after. A minority of banks sell add-on CDs that accept additional deposits, and this calculator supports that case with the monthly addition field. If your money arrives gradually, a better structure is often a CD ladder, where you open several CDs of staggered terms as the cash becomes available.
CDs at banks are insured by the FDIC and CDs at credit unions by the NCUA, in both cases up to $250,000 per depositor, per institution, per ownership category. Amounts above that line are exposed if the institution fails, so large deposits are usually split across banks or held in different ownership categories, such as one account individually and one jointly.
All calculation logic on this page is implemented from the primary documents below. Each one is listed with the figure it supplies, so any rate or threshold in the result can be traced back to its published source.
Same compounding math, different starting question.