CD Calculator

How to use the CD calculator

A certificate of deposit (CD) is a savings account with a fixed term: you leave a lump sum with a bank or credit union for, say, 12 months, and in return it pays a rate that is set when you open the account. This CD calculator works out where that deposit ends up. It opens with an example already filled in, $10,000 at 4.00% APY for 12 months, compounded daily. The rate is only an illustration, not a quote; type the APY from the offer you are looking at and every result updates as you type.

1. Enter the deposit. The amount you plan to put in. You can type 25000, $25,000 or 25k.
2. Enter the rate, and say which kind it is. Most offers lead with the APY (annual percentage yield). If you only have the stated interest rate, flip the switch to Interest rate. The results always show both, so the tool doubles as an APY calculator and a CD rate calculator.
3. Pick the compounding. Daily, monthly, quarterly, semiannually, annually, continuously, or none (simple interest). The account disclosure says which one applies. If you entered an APY, compounding barely matters, as explained below.
4. Set the term in months, days or years, or tap a quick term such as 6 months or 5 years.
5. Add taxes and inflation if you like. Under Taxes & inflation, enter your combined federal and state marginal tax rate and an inflation rate to see after-tax interest and what the maturity value is worth in today's dollars.
6. Read the results. You get the balance at maturity, the interest earned, the APY and the equivalent interest rate, a growth chart and a monthly or yearly schedule. Copy the results, download the schedule as a CSV file or print it.

Three more tabs cover the other questions people ask about CDs. CD ladder is a CD ladder calculator: it splits a sum across several CDs that mature at different times. Compare CDs puts up to four offers side by side and tells you which one comes out ahead and on what basis. Early withdrawal is a CD early withdrawal penalty calculator: it shows what you would get back if you closed a CD today, and the rate you would need elsewhere for breaking it to pay off.

How CD interest is calculated

Every CD interest calculator, this one included, comes down to one idea: interest is added to the balance, and later interest is earned on that interest too. How often that happens is the compounding frequency. With a deposit P, a stated annual interest rate r (as a decimal, so 4.5% is 0.045), n compounding periods a year and a term of t years:

balance at maturity = P × (1 + r ÷ n)^(n × t)       n = 365 daily, 12 monthly, 4 quarterly, 2, 1
continuous          = P × e^(r × t)
no compounding      = P × (1 + r × t)               simple interest
from an APY         = P × (1 + APY)^t               any compounding
interest earned     = balance at maturity − P
t                   = months ÷ 12, or days ÷ 365

The last formula is the one most people need, because banks advertise the APY. An APY is the yield for one year with compounding already included, so to grow a deposit by an APY you only raise (1 + APY) to the number of years. The compounding frequency drops out.

Example 1: $10,000 at 4.00% APY for 12 months

One year at 4.00% APY: $10,000 × 1.04 = $10,400.00, so the CD earns $400.00. That holds whatever the compounding. If the bank compounds daily, the interest rate behind that APY is 3.9223%; if it compounds monthly, it is 3.9285%. The bank has to quote the APY, and the APY is what tells you the result.

Example 2: the same CD for 5 years

Five years at 4.00% APY: $10,000 × 1.04⁵ = $12,166.53, or $2,166.53 of interest. Without compounding, five years of $400 would be $2,000; the extra $166.53 is interest on interest. That gap grows with the term, which is why compounding matters far more on a 5-year CD than on a 6-month one.

Example 3: a 4.50% interest rate, compounded daily, for 18 months

Here the offer gives the stated rate, not the APY. Eighteen months is 1.5 years, and daily compounding means 365 periods a year: $10,000 × (1 + 0.045 ÷ 365)^547.5 = $10,698.26, which is $698.26 of interest. The APY of a 4.50% rate compounded daily is (1 + 0.045 ÷ 365)³⁶⁵ − 1 = 4.60% (4.6025% before rounding). A bank that counts the term as 547 or 548 actual days will land under a dollar either side of that figure.

APY vs. interest rate

The interest rate (also called the nominal or stated rate) is the annual rate the bank applies before compounding. The annual percentage yield (APY) is what that rate actually earns in a year once compounding is counted. For any compounding more often than once a year, the APY is a little higher than the rate:

APY           = (1 + r ÷ n)^n − 1        continuous: e^r − 1
interest rate = n × ((1 + APY)^(1 ÷ n) − 1)   continuous: ln(1 + APY)

Under the Truth in Savings Act, a bank must disclose the APY, and if you ask about rates it has to state the APY; it may add the interest rate, but no other rate may be quoted (Regulation DD, 12 CFR 1030.3(e)). The APY is rounded to two decimal places, so 5.644% is disclosed as 5.64% and 5.645% as 5.65% (§1030.3(f) and its official interpretation). That makes the APY the number to compare between offers: two CDs with the same APY and term earn the same, even if one compounds daily and the other monthly.

The flip side is that compounding frequency matters less than people think. Going the other way, a 4.00% APY is a 3.92% interest rate compounded daily, 3.93% compounded monthly, 3.94% compounded quarterly and 4.00% compounded annually: each bank sets its rate so that the yield comes out the same. Over 18 months, $10,000 at 4.00% APY grows to $10,605.96 with daily compounding and to $10,605.96 with monthly compounding. Compounding only changes the result when you hold the interest rate fixed, which is what the next table does.

Compounding frequency compared

Take a 4.50% interest rate on $10,000 for one year and change only how often interest is compounded. More frequent compounding earns more, but the steps shrink quickly: daily compounding beats monthly by under a dollar on $10,000, and continuous compounding, the mathematical limit, adds only cents more.

Is CD interest compounded daily or monthly? It depends on the institution: Regulation DD does not require any particular compounding or crediting schedule, only that it is disclosed (12 CFR 1030.7). Many banks compound daily or monthly. When an offer states only the interest rate, choose the matching compounding in the calculator; when it states the APY, any choice gives the same balance.

Simple vs. compound interest on a CD

Some CDs do not compound at all. Interest is paid out to a checking or savings account each month, quarter or year, or it accrues as simple interest and is paid in one lump at maturity. Brokered CDs, which you buy through a brokerage account, generally pay simple interest rather than compound interest, according to the SEC's investor bulletin on brokered CDs. With simple interest the formula is just principal × rate × time.

Over five years the difference is real. $10,000 at a 5.00% interest rate with no compounding ends at $12,500.00. Compounded once a year it ends at $12,762.82, and compounded daily at $12,840.03, $2,840.03 of interest instead of $2,500.00.

If you have the interest paid out monthly to spend, choose None (simple interest) and enter the stated Interest rate in the calculator to see the total you will receive; the deposit itself stays the same. If you reinvest those payments yourself, the result lands between the two.

How much will $10,000 earn in a CD?

The answer depends on just two things: the APY and how long you leave the money in. The table shows the interest $10,000 earns at three example APYs. They are round numbers chosen for illustration, not current or average rates, which change constantly; use the calculator with the rate you are actually offered. Add $10,000 to any figure for the balance at maturity.

Notice that 6 months at 5.00% APY earns $246.95, not half of $500. The APY is a one-year figure that includes a full year of compounding; half a year earns slightly less than half of it.

How much does a $5,000, $50,000 or $100,000 CD earn?

For a fixed APY and term, interest scales in a straight line with the deposit. At an example 4.00% APY for one year:

Taxes on CD interest

CD interest is taxed as ordinary income at your marginal rate, the same as wages. Interest, including CD interest, is taxable in the year it becomes available to you (IRS Topic 403). Interest from a bank or credit union CD is generally taxable by your state as well. A few rules are specific to CDs:

• Forms 1099-INT and 1099-OID. If you earn $10 or more of interest, the institution sends you a Form 1099-INT or 1099-OID. You owe tax on all interest, with or without a form.
• CDs longer than a year are taxed every year. According to IRS Publication 550, if you buy a CD with a maturity of more than one year, you must include in income each year a part of the total interest due, as original issue discount (OID), even if the bank only pays it at maturity. You may owe tax on a 5-year CD long before you can spend the interest.
• Early withdrawal. If you break a CD early, you report all of the interest credited during the year without subtracting the penalty. The penalty appears on Form 1099-INT (box 2) and is deductible on Schedule 1 (Form 1040), "Penalty on early withdrawal of savings" (Publication 550).
• Retirement accounts. A CD held inside a traditional IRA or a Roth IRA follows that account's tax rules instead, so its interest is not taxed year by year.

To estimate after-tax interest, open Taxes & inflation in the calculator and enter your combined federal and state marginal rate. The tool applies it to the total interest, which assumes you pay the tax each year from other money rather than out of the CD; if the tax came out of the CD every year, the balance would compound a little less. This is an estimate, not tax advice. For your own situation, check with a tax professional.

Inflation and your real return

A CD's dollars are fixed; what they buy is not. The real return is what is left after inflation, and for a CD it is roughly the APY minus the inflation rate. Exactly:

real annual return        = (1 + APY) ÷ (1 + inflation) − 1
value in today's dollars  = balance at maturity ÷ (1 + inflation)^t

The calculator does not guess inflation; you type a rate. The consumer price index from the Bureau of Labor Statistics is the usual reference for past inflation.

Example: $25,000 for 5 years, with taxes and inflation

A $25,000 CD pays a 4.00% interest rate compounded monthly, which is an APY of 4.0742%. After 5 years it is worth $30,524.91, with $5,524.91 of interest. At an example combined marginal tax rate of 22%, the tax on that interest is $1,215.48, leaving $4,309.43 and an after-tax balance of $29,309.43, an after-tax yield of 3.23% a year. With 3% inflation each year, that after-tax balance is worth $25,282.57 in today's dollars, a real return of only 0.23% a year. Before tax, the real value would be $26,331.06, or 1.04% a year.

None of that means the CD lost money. It means a CD protects your principal from loss, not from inflation, and taxes take a share of the interest before inflation takes its share of what remains. Comparing that real return against your goals is the honest way to judge a CD.

CD ladders

A CD ladder splits one sum into several CDs with staggered maturities, so part of your money comes free at regular intervals instead of all of it being locked up until one date. When a rung matures you either use the money or roll it into a new CD at the longest term in the ladder. After the first cycle, one CD matures every interval and each new rung earns the longer-term rate, which has historically often been higher, though not always.

Example: $50,000 in a 5-rung ladder

The CD ladder tab opens with this ladder: $50,000 split into five $10,000 CDs maturing in 1, 2, 3, 4 and 5 years, at example APYs that rise with the term.

The total row's APY is the deposit-weighted average of the five rungs. The first $10,000 is available after one year instead of five, which is the point of a ladder: you trade a little yield on the short rungs for regular access and the chance to reinvest at whatever rates are on offer later. The tool also builds ladders with rungs every 3 or 6 months, and you can type your own APY for each rung.

Early withdrawal penalties

Taking money out of a CD before it matures usually costs a penalty, most often stated as a number of days' or months' worth of interest. Each institution sets its own rule, and it must disclose the penalty before you open the account (12 CFR 1030.4). Longer CDs tend to carry larger penalties. The ranges below are common, not a rule; your account disclosure is the only source that counts.

The most common wording, "N days of simple interest," works out as deposit × interest rate × N ÷ 365, and that is how the calculator models it by default. Some banks compute it on the APY instead, so set the basis to match your disclosure. Others charge it only on the amount withdrawn; for a partial withdrawal, enter that amount as the deposit.

Example: breaking a 2-year CD after 9 months

You put $10,000 in a 24-month CD at 4.00% APY, compounded daily, with a penalty of 180 days of simple interest. After 9 months it is worth $10,298.52. The penalty is $10,000 × 3.9223% × 180 ÷ 365 = $193.43, so closing the CD pays out $10,105.10. You keep your principal, but most of the interest is gone. Kept to maturity, the CD would have been worth $10,816.00. To beat that, the $10,105.10 would have to earn at least 5.59% APY for the remaining 15 months. At 5.00% APY it would grow to only $10,740.56, leaving you $75.44 behind, so in this case keeping the CD wins.

When the penalty eats into principal

A penalty can be larger than the interest earned so far, and then it comes out of your deposit. Take a 5-year, $10,000 CD at a 4.00% interest rate compounded daily, with a penalty of 365 days of simple interest, closed after 243 days. It has earned $269.86, but the penalty is $400.00, so you get back $9,869.86, which is $130.14 less than you put in. Held for the full 5 years, it would reach $12,213.89; breaking it only pays if the proceeds can earn about 5.04% APY for the rest of the term. With a 180-day penalty of $197.26 instead, the break-even falls to 4.55% APY.

The Early withdrawal tab runs these numbers for your own CD and penalty, including the break-even APY. Penalty rules vary, so check your account disclosure before you act.

CDs vs. high-yield savings vs. Treasury bills

All three are low-risk places for cash, and the right one depends on when you need the money and whether you want the rate locked. In plain terms:

A CD suits money with a known date, such as a down payment a year away, and it protects you if rates fall, because your rate is fixed. A high-yield savings account suits an emergency fund: the rate can move at any time, but the money is there when you need it. Treasury bills, bought through TreasuryDirect or a brokerage, are exempt from state and local income tax, so in a high-tax state a T-bill can come out ahead of a CD with a slightly higher yield. Compare on an after-tax basis, using each option's APY or yield for the same period.

FDIC and NCUA insurance

CDs at banks are covered by the FDIC: the standard amount is "$250,000 per depositor, per FDIC-insured bank, for each account ownership category" (FDIC, Understanding Deposit Insurance). Credit union share certificates have the same limit from the NCUA (MyCreditUnion.gov, Your Insured Funds): "The $250,000 in coverage applies to each share owner, per insured credit union, for each account ownership category." Coverage includes principal and interest accrued up to the date of a failure, up to the insurance limit (FDIC, Your Insured Deposits).

• Ownership categories count separately. Single accounts, joint accounts, certain retirement accounts and trust accounts each have their own limit at the same bank, so a household can be insured for well over $250,000 at one institution.
• Trust accounts. Under the rule in effect since April 1, 2024, trust deposits are insured up to $250,000 per owner for each eligible beneficiary, up to $1,250,000 per owner per bank (FDIC EDIE).
• Check your own coverage with the FDIC's Electronic Deposit Insurance Estimator (EDIE) or the NCUA's Your Insured Funds guide.
• Brokered CDs are insured only if the bank that issued them is insured and the broker records your ownership correctly (FDIC, Your Insured Deposits).

Above the limit, spread larger sums across institutions or ownership categories. That matters most with jumbo CDs.

Types of CDs

• Traditional CD. A fixed rate for a fixed term, with a penalty for early withdrawal.
• No-penalty CD. Lets you withdraw after an initial waiting period without a penalty, usually in exchange for a lower rate.
• Bump-up or raise-your-rate CD. Lets you ask for a higher rate, usually once, if the bank's rate for your term goes up. Starting rates tend to be lower.
• Step-up CD. The rate rises on a set schedule. Compare it by its APY for the whole term, which the bank must disclose.
• Jumbo CD. A CD with a high minimum deposit, often $100,000 or more, sometimes at a slightly better rate. Watch the insurance limit.
• Add-on CD. Accepts extra deposits during the term.
• Brokered CD. Bought through a brokerage. It usually has no early withdrawal penalty; instead you sell it on the secondary market, where you may get less than you paid, pay a fee, or find no buyer. Some are callable, meaning the bank can end them early when rates fall. See the SEC's brokered CD bulletin.
• IRA CD. A CD held inside an individual retirement account, taxed under IRA rules.

How we calculate

Every figure on this page and in the tool comes from the same code, and the examples above are checked against it automatically. These are the assumptions behind it:

• A 365-day year. A term in days is days ÷ 365 years; a term in months is months ÷ 12. Regulation DD lets banks use a 365-day year, or 366 days in a leap year, and to count actual calendar days (Appendix A to 12 CFR 1030).
• Fractional periods accrue. Banks must calculate (accrue) interest on the full amount of principal for each day, at a daily rate of at least 1/365 of the interest rate (12 CFR 1030.7), so we let the exponent n × t be a fraction rather than rounding down to whole compounding periods. That is an approximation: between compounding dates banks usually accrue simple daily interest, so for an infrequently compounded CD on a term that isn't a whole number of periods, our figure can differ from the bank's by cents to a few dollars.
• An APY is an APY. When you enter an APY, the balance is P × (1 + APY)^t for every compounding setting, none included; the compounding choice only changes the equivalent interest rate shown. With no compounding, that rate is the simple rate that earns the same total over the term, ((1 + APY)^t − 1) ÷ t, so the APY the tool reports is the one you typed, as the Regulation DD formula gives for that CD. A CD longer than a year that pays its interest out at least once a year may disclose an APY equal to its rate; for one of those, choose Interest rate.
• Taxes are your marginal rate times the total interest, paid from other funds. Inflation is a constant annual rate you choose.
• Day counts explain small differences. A 6-month CD can be 181 to 184 days. At 5.00% APY, $10,000 earns $246.95 over exactly half a year, $246.27 over 182 days and $247.64 over 183 days. If your bank's figure is a few cents or dollars away from ours, its day count is usually why.

The APY the tool reports follows the Regulation DD definition: APY = 100 × [(1 + interest ÷ principal)^{(365 ÷ days in term)} − 1]. Two examples from the regulation itself: $1,000 that earns $61.68 over 365 days has an APY of 6.17%, and $1,000 that earns $30.37 in a 182-day CD has an APY of 6.18%.

A CD calculator handles one lump sum. For regular deposits, a savings calculator or compound interest calculator that takes monthly contributions is the better tool; for a loan or a non-compounding note, a simple interest calculator.

Your numbers stay on your device

Every calculation on this page runs as JavaScript in your own browser tab. There is no server doing the math, and there is no live rate feed: you type the rates.

• Nothing is uploaded. The tool has no code that sends data anywhere, and the page's Content-Security-Policy only allows connections back to this site. Open your browser's developer tools, choose the Network tab and change a few numbers: no request appears.
• It keeps working offline. Once the page has loaded, you can disconnect and keep calculating.
• No account, no cookies. The tool remembers your last inputs and tab in your browser's local storage, on your device only.

Sources

• Regulation DD (Truth in Savings), Appendix A: annual percentage yield calculation, 12 CFR 1030, Consumer Financial Protection Bureau.
• 12 CFR 1030.3: general disclosure requirements, including rate inquiries (e) and rounding (f).
• 12 CFR 1030.4: account disclosures, including early withdrawal penalties.
• 12 CFR 1030.7: payment of interest, daily accrual and compounding.
• 12 CFR Part 1030 on eCFR, the official text.
• IRS Topic 403: Interest received.
• IRS Publication 550: Investment income and expenses, including CDs, OID and the early withdrawal penalty.
• FDIC: Understanding deposit insurance and EDIE, the Electronic Deposit Insurance Estimator.
• NCUA: Share insurance FAQ and Your Insured Funds.
• SEC Investor.gov: Brokered CDs investor bulletin.
• TreasuryDirect: Treasury bills.
• U.S. Bureau of Labor Statistics: Consumer Price Index.

Reviewed by microplugins · Last updated October 10, 2026

This is an educational tool, not financial or tax advice. Rates on this page are examples, not offers or current rates. Your bank's day count, compounding and penalty rules decide the exact figures; read your account disclosure.