What is APY on a CD, and how is it different from the interest rate?

The interest rate — sometimes called the nominal rate or APR — is the headline rate before compounding. APY, the annual percentage yield, is what you actually earn over a year once interest starts earning interest: APY = (1 + r/n)^n − 1. APY is always at least as high as the nominal rate, and US banks are required to disclose APY on deposit accounts so you can compare two CDs with different compounding schedules on equal footing.

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

At a 4.50% APY, $10,000 grows to about $10,450 after one year and about $12,462 after five, earning roughly $450 and $2,462 in interest. Halve the rate and you roughly halve the interest; double the term and you slightly more than double it, because the interest compounds. The quick chart on this page shows the balance and the interest for deposits from $1,000 to $100,000 at every APY from 0.50% to 6.00%.

What is the penalty for withdrawing from a CD early?

Almost every US bank states the penalty as a number of months of interest on the amount withdrawn, priced at the CD's own rate: commonly three months on terms of a year or less, six months on terms up to about four years, and twelve months or more on longer ones. The penalty is not capped at the interest you have actually earned, so cashing out early in the term can hand back less than you deposited.

Can you lose money on a CD?

Within federal insurance limits you cannot lose your deposit to a bank failure, but you can lose money two other ways. Breaking the CD before you have accrued enough interest to cover the early-withdrawal penalty eats into principal. And if inflation runs higher than your APY, the balance grows in dollars while shrinking in purchasing power, which is the more common way savers lose ground.

Is CD interest taxable?

Yes. In the United States interest on a CD held in a taxable account is ordinary income, taxed at your marginal rate in the year it is credited — not the year the CD matures. The bank reports it on Form 1099-INT once it exceeds ten dollars. A multi-year CD therefore generates a tax bill each year even though you cannot touch the money. Interest inside an IRA CD is tax-deferred or tax-free instead. This is general information, not tax advice.

A ladder splits one pot across several CDs that mature a year apart — for example five equal slices at one, two, three, four, and five years. As each rung matures you roll it into a fresh five-year CD. After the first cycle every rung is earning the long-term rate, yet one of them is always within twelve months of maturing, so you get the higher yield without locking everything away.

Does compounding frequency matter on a CD?

Less than most people expect, and it is already accounted for if you compare accounts on APY. Daily compounding beats annual compounding on the same nominal rate, but the gap is a few hundredths of a percentage point — the rate and the term do almost all the work. Compare CDs on the advertised APY and the frequency question answers itself.

Are CDs FDIC insured?

CDs at an FDIC-member bank, and share certificates at an NCUA-member credit union, are federally insured up to the standard limit of $250,000 per depositor, per institution, per ownership category. The insurance covers both the principal and the interest accrued up to that limit. Brokered CDs pass the insurance through to the issuing banks, which is worth confirming before you buy one.

Finance

CD Calculator

A certificate of deposit grows by A = P(1 + r/n)^(nt) — your deposit, the rate, how often it compounds, and the term. Enter yours for the value at maturity, the interest earned, and the effective APY, or flip the mode to solve back for the rate, deposit, or term you need.

Your CD

Solve for

Deposit amount

What you put into the CD

Interest rate

The APY on the bank's rate sheet

That rate is:

Term

How long the money is locked up

Compounding frequency

How often the bank credits interest

Value at maturity · 1 yr

$10,450.00

$450.00 of interest on $10,000 over 1 yr

Deposit $10,000Interest $450At maturity $10,450

Interest earned

$450

Interest vs deposit

4.5%

Effective APY

4.50%

Nominal rate

4.41%

Balance through the term

Deposit Interest12mo → $10,450

Try a scenario

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The basics

What is a certificate of deposit?

A CD is a savings account with a deadline. You hand a bank a fixed amount for a fixed term, the bank fixes your rate for that whole term, and you agree not to touch the money until it matures. In exchange for giving up access you get a higher, guaranteed yield than an ordinary savings account, and the rate cannot be cut underneath you. Two ideas explain everything a CD does.

A = P(1 + r/n)^(nt)

A locked rate, compounding

The balance A grows from your deposit P at the nominal rate r, credited n times a year for t years. Each credit joins the balance and starts earning too, which is why the last month of a term earns more than the first.

$10,000 at 4.50% APY for 1 yr → $10,450.00

liquidity traded for yield

The lock-up is the product

The bank pays extra because it knows exactly how long it has your money. Take it back early and you pay that premium back as an early-withdrawal penalty, which is the one term of a CD worth reading before you sign.

Cashing the same CD at 3 months against a 6-month penalty → $9,890.16, below the $10,000 deposit

Method

How to calculate CD interest by hand

Four steps take you from a rate sheet to the number the bank will hand back at maturity.

1
Write down the four inputs
You need the deposit P, the rate, the compounding frequency n, and the term t converted to years. Divide a term quoted in months by twelve.
P = 10000, APY = 4.50%, n = 12, t = 1
2
Turn the advertised APY into a nominal rate
Rate sheets quote APY, but the formula wants the nominal rate r. Invert the yield definition to recover it. Skip this step if your bank quoted the nominal rate directly.
r = 12 × ((1.045)^(1/12) − 1) = 4.410%
3
Find the rate per period and the period count
Divide the nominal rate by the number of credits per year, and multiply the frequency by the term to count how many times interest is added.
r/n = 4.410% ÷ 12 · nt = 12 × 1 = 12
4
Apply the formula, then subtract the deposit
Add one to the periodic rate, raise it to the period count, and multiply by P. Subtracting P isolates the interest the CD actually paid you.
$10,000 × (1 + r/n)^12 = $10,450.00 · interest $450.00

Worked examples

The same deposit across four terms

One deposit, one APY, one compounding schedule — only the lock-up changes. Switch tabs to watch the working and the answer move.

Given P = $10,000.00, APY = 4.50%, n = 12, t = 1 years

APY → nominal rate: 12 × ((1 + 0.045)^(1/12) − 1) = 4.4098%

Rate per period: 4.4098% ÷ 12 = 0.003675

Number of periods: 12 × 1 = 12

Apply formula: A = $10,000.00 × (1 + 0.003675)¹²

A = $10,450.00

interest = $450.00

Same deposit, same yield — only the lock-up changes. Because the interest keeps compounding on itself, the five-year term earns far more than ten times the six-month term, not five times.

Apy vs apr

Why a CD quotes two different rates

The single most common confusion on a rate sheet. The interest rate and the annual percentage yield describe the same CD, but only one of them is the number you actually earn — and only one of them is safe to compare across banks.

the headline rate

Interest rate (nominal, or APR)

The rate before compounding is folded in. It is what the bank multiplies your balance by each period, so on its own it understates what a year in the CD is worth — and it means nothing until you also know how often interest is credited.

A 4.50% nominal rate compounded daily yields 4.60% APY

APY = (1 + r/n)ⁿ − 1

Annual percentage yield (APY)

The true yearly return once interest starts earning interest. Because US banks must disclose it on deposit accounts, comparing two CDs on APY is an apples-to-apples comparison no matter how differently they compound.

To advertise 4.50% APY with monthly credits a bank runs 4.410% nominal

Compounding	n / year	APY from a 4.50% nominal rate	Nominal rate behind a 4.50% APY
Daily	365	4.602%	4.402%
Monthly	12	4.594%	4.410%
Quarterly	4	4.577%	4.426%
Semi-annually	2	4.551%	4.450%
Annually	1	4.500%	4.500%

The whole spread from annual to daily compounding is about 0.10% of yield — real, but far smaller than a quarter-point difference in the rate itself.

Breaking the cd

What an early withdrawal really costs

The part of a CD nobody front-loads. Set your deposit, rate, term, and the penalty printed in the disclosure, then slide the exit month to see what you would actually walk away with — and when the penalty starts eating principal.

Deposit

APY

CD term

Penalty stated in the disclosure

Cash out after month 9 of 24

You would walk away with

$10,115.15

$115.15 more than you deposited

Interest accrued

$335.64

Penalty charged

−$220.49

Yield you realise

1.54%

If you had held on

$10,920

The penalty is priced as simple interest at the CD's own rate on the money you take out, for the number of months in the disclosure — it is not capped at the interest you have actually earned. Break the CD before you have accrued that much, and the bank takes the shortfall out of your principal.

months of interest

How the penalty is priced

The disclosure states a number of months of interest on the amount withdrawn, charged at the CD's own rate. It is not a flat fee and not a share of the balance.

not capped at interest earned

Why principal can shrink

If you leave before you have accrued the stated months of interest, the bank still charges the full amount and takes the shortfall out of your deposit.

no-penalty CDs exist

The way around it

Some banks sell a no-penalty CD that can be closed after a short waiting period. You give up part of the yield for the right to change your mind.

Strategy

Build a CD ladder

A ladder is the standard answer to the central problem with CDs: long terms pay more, but lock your money away for longer. Split the pot into rungs maturing a year apart and you collect long-term rates while something always comes due within twelve months.

Total to invest

Number of rungs

Each rung gets $10,000. Edit any APY to match what your own bank is quoting for that term — the rates below are only starting points.

Rung	Term	Amount	APY	Interest	At maturity
#1	1 yr	$10,000	%	$400	$10,400
#2	2 yrs	$10,000	%	$826	$10,826
#3	3 yrs	$10,000	%	$1,281	$11,281
#4	4 yrs	$10,000	%	$1,766	$11,766
#5	5 yrs	$10,000	%	$2,284	$12,284

Invested

$50,000

Total interest

$6,557.71

Value when all mature

$56,558

Blended APY

4.10%

Once the ladder is running, the one-year rung matures first and is normally rolled into a fresh 5-year CD. Repeat that each year and every rung ends up earning the longest rate while one of them is always within twelve months of maturing.

Reference

Common CD terms and their penalties

The term ladder almost every US bank publishes, the penalty tier each term usually falls into, and what a given term is normally used for. Penalties vary by institution — always read your own disclosure.

Term	Months	Typical penalty	Usually used for
3 months	3	3 months of interest	Parking cash you may need this quarter
6 months	6	3 months of interest	A short hold with a rate lock
9 months	9	3 months of interest	Often a promotional teaser term
1 year	12	3 months of interest	The most popular term by far
18 months	18	6 months of interest	A common promotional term
2 years	24	6 months of interest	Money earmarked for a known purchase
3 years	36	6 months of interest	The middle rung of most ladders
4 years	48	12 months of interest	Locking a rate you expect to fall
5 years	60	12 months of interest	The longest rung most savers use

Quick chart

How much will a CD pay?

Pick a deposit and read the balance — or the interest alone — at every APY from half a percent to six, across five terms. The answer to “how much interest will $X earn in a CD” for well over a thousand combinations.

Deposit

Show

Balance at maturity on $10,000, by APY and term.

APY	6 months	1 year	2 years	3 years	5 years
0.50%	$10,025	$10,050	$10,100	$10,151	$10,253
0.75%	$10,037	$10,075	$10,151	$10,227	$10,381
1.00%	$10,050	$10,100	$10,201	$10,303	$10,510
1.25%	$10,062	$10,125	$10,252	$10,380	$10,641
1.50%	$10,075	$10,150	$10,302	$10,457	$10,773
1.75%	$10,087	$10,175	$10,353	$10,534	$10,906
2.00%	$10,100	$10,200	$10,404	$10,612	$11,041
2.25%	$10,112	$10,225	$10,455	$10,690	$11,177
2.50%	$10,124	$10,250	$10,506	$10,769	$11,314
2.75%	$10,137	$10,275	$10,558	$10,848	$11,453
3.00%	$10,149	$10,300	$10,609	$10,927	$11,593
3.25%	$10,161	$10,325	$10,661	$11,007	$11,734
3.50%	$10,173	$10,350	$10,712	$11,087	$11,877
3.75%	$10,186	$10,375	$10,764	$11,168	$12,021
4.00%	$10,198	$10,400	$10,816	$11,249	$12,167
4.25%	$10,210	$10,425	$10,868	$11,330	$12,313
4.50%	$10,223	$10,450	$10,920	$11,412	$12,462
4.75%	$10,235	$10,475	$10,973	$11,494	$12,612
5.00%	$10,247	$10,500	$11,025	$11,576	$12,763
5.25%	$10,259	$10,525	$11,078	$11,659	$12,915
5.50%	$10,271	$10,550	$11,130	$11,742	$13,070
5.75%	$10,283	$10,575	$11,183	$11,826	$13,225
6.00%	$10,296	$10,600	$11,236	$11,910	$13,382

APY already includes compounding, so these figures hold whether the bank compounds daily, monthly, or quarterly.

Varieties

The kinds of CD you will be offered

Banks shelve half a dozen products under the same three letters. They price differently because they hand you different rights, so the headline rate alone will not tell you which is the better deal.

Traditional CD: A fixed rate for a fixed term with a stated early-withdrawal penalty. Everything else on this list is a variation on it.
No-penalty CD: Can be closed after an initial waiting period with no penalty, in exchange for a lower rate. Useful when you might need the money back.
Bump-up CD: Lets you raise your rate once, or sometimes twice, if the bank's rate for that term goes up. It starts below the traditional rate.
Step-up CD: Moves to a higher rate on a schedule set at the start. The advertised headline rate is the last step, not the average.
Jumbo CD: A traditional CD with a large minimum, historically a hundred thousand dollars. The rate premium over a standard CD is often small.
Brokered CD: Bought through a brokerage rather than a bank. It can be sold on a secondary market instead of surrendered, so the exit price moves with rates.
IRA CD: A CD held inside a retirement account, so the interest is tax-deferred or tax-free rather than taxed in the year it is credited.
Callable CD: The bank may end it early and return your money, usually after rates fall. You keep the interest earned but lose the rate you locked.

Where it shows up

When a CD is the right tool

A CD is a poor general-purpose savings account and an excellent instrument for money with a date attached.

a known date

Money you already spent

A down payment, a tax bill, a wedding. The horizon is fixed, so the lock-up costs you nothing and the guaranteed rate removes the risk of a market dip at the wrong moment.

rates expected to fall

Locking a rate in

Savings-account rates float and can be cut overnight. A CD fixes your yield for the whole term, which is worth most when everyone expects rates to come down.

capital preservation

The cautious slice

For the part of a portfolio that must not fall in value, an insured CD delivers a stated return with no price risk — at the cost of no upside either.

Tax

How CD interest is taxed

Every figure this calculator produces is pre-tax. In the United States, CD interest in a taxable account is ordinary income, and the timing catches people out on multi-year CDs. This is general information, not tax advice — check your own situation with a professional.

taxed as ordinary income

Your marginal rate, not a capital-gains rate

Interest is added to your income for the year, so it is taxed at whatever bracket that income falls into. There is no preferential rate the way there is for long-held stock.

$2,461.82 of interest over five years is taxed in the years it is credited

reported on Form 1099-INT

Taxed as it accrues, not at maturity

A multi-year CD generates a tax bill every year even though you cannot withdraw the money to pay it. Holding the CD inside a retirement account defers or removes that, which is the main reason IRA CDs exist.

A bank issues the form once interest for the year passes $10

Worth knowing

Rules worth remembering

Six things that decide whether a CD was a good idea, none of which appear on the rate sheet.

compare on APY, never the rate

One number does the comparing

APY already contains the compounding schedule, so it is the only figure that lets two CDs from different banks be judged side by side.

compounding beats a straight line

Interest earns interest

A CD is not a flat annual payout. Each credited amount joins the balance, so the back half of a long term earns noticeably more than the front half.

Five years at 4.50% pays $211.82 more than simple interest would

real return = APY − inflation

Inflation is the real hurdle

A guaranteed yield below the inflation rate is a guaranteed loss of purchasing power. Judge a CD against inflation, not against zero.

auto-renewal is the default

Watch the maturity window

Most CDs roll into a new term automatically unless you act inside a short grace period, and the renewal rate is often well below what you could get shopping around.

$250,000 per depositor, per bank

Insurance has a ceiling

Federal insurance covers principal plus accrued interest up to the standard limit at each institution. Above it, split the money across banks or ownership categories.

a rung every year

A ladder beats guessing

Rather than betting on where rates go, a ladder gives you a slice of the long rate and a regular chance to reinvest at whatever the new rate turns out to be.

FAQ

Common questions

A certificate of deposit uses the compound interest formula A = P(1 + r/n)^(nt), where P is your deposit, r is the nominal annual rate as a decimal, n is how many times a year the bank credits interest, and t is the term in years. The interest you earn is A − P. Because banks advertise APY rather than the nominal rate, the shortcut is even simpler: at maturity a CD is worth P × (1 + APY)^t, since APY already has the compounding baked in.

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