How Much Interest Does $10,000 Earn in a CD?

At a hypothetical 5% APY, $10,000 in a CD earns $122.72 in three months, $246.95 in six months, $500.00 in twelve months and $1,576.25 in three years. The rate is an annual figure, so the dollar answer depends on how long the money stays in. This guide shows the arithmetic behind those numbers, what changes them, and how to check a real offer against its paperwork. Every rate here is an example, not a quote or a forecast.

What $10,000 earns at a hypothetical 5% APY

Assume one deposit of $10,000, a fixed 5% APY, no additional deposits, no withdrawals, no tax and no fees. APY, the annual percentage yield, already includes compounding. Here is what that deposit becomes:

Take the twelve-month row first: with an APY, one year of interest is simply the deposit times the APY, here $10,000 times 5%. Longer terms earn interest on interest, which is why 36 months pays $1,576.25 rather than $1,500.00.

Changing the yield moves every row. Same deposit, same terms, three hypothetical APYs:

Each percentage point of APY is worth $100 on $10,000 over a single year. Over three months the same point is worth only about $24.

To run your own deposit, rate and term, calculate your CD's maturity value in the free CD calculator.

Why a three-month CD does not earn a full year's yield

The formula behind the table is short. With an effective annual yield a, a deposit P and a term of m months:

Maturity = P × (1 + a)^(m / 12)

For three months at 5%, that is $10,000 × 1.05^(3/12) = $10,122.72. The exponent is a fraction of a year because APY is the growth over a full year, not over any shorter period.

Two shortcuts give slightly wrong answers:

For this positive APY, linear prorating ignores compounding. The equivalent three-month yield is 1.05^(1/4) − 1, about 1.2272%, rather than 5% ÷ 4 = 1.25%.

Banks do not count in neat months. Regulation DD, which governs how banks disclose APY, generally calculates it from the number of days in the term using a 365-day year; a 366-day basis is permitted in a leap year. A 182-day CD at a 5% APY earns about $246.27 on $10,000, and a 91-day CD about $122.38. These two day-based examples differ from the month-based table by less than a dollar; other terms, rate rounding and crediting rules can produce different gaps. Treat the calculator as an estimate to check against your disclosure, not as the bank's posted balance.

The same formula runs backward. Regulation DD defines APY as (1 + interest ÷ principal) raised to the power 365 ÷ days in term, minus 1. The regulation's own example is a six-month CD that pays $30.37 on $1,000 over 182 days, which works out to an APY of 6.18%. Applied to a hypothetical CD that pays $150.00 on $10,000 over 91 days, the same formula gives an APY of about 6.15%. If a bank shows you dollars of interest but not the yield, you can recover the yield yourself.

APY versus a nominal interest rate

The most common way to overstate CD interest is mixing up two different quotes.

• An APY is the effective yield after compounding. It already contains the compounding, so you apply it once.
• A nominal rate is quoted before compounding and comes with a schedule, such as monthly. You have to compound it yourself.

A nominal 5% compounded monthly is not the same offer as a 5% APY. Its effective yield is about 5.1162%, so $10,000 earns $511.62 in twelve months instead of $500.00. A quick way to produce that larger figure by mistake is to take a 5% APY, divide it by twelve and compound monthly. That treats the APY as a nominal rate and double-counts compounding, adding $11.62 of interest that the offer does not pay.

The practical rule is to compare APY with APY. If an offer lists only a nominal rate and a compounding schedule, convert it first with the APR and APY calculator and then compare. In the CD calculator, choose "APY (effective rate)" when you have an APY; the compounding control is hidden in that mode because it does not matter.

What taxes and early withdrawal can change

The results above are gross, before tax and before any penalty. Two real-world costs sit outside the table.

Tax. The IRS lists interest on certificates of deposit among taxable interest income and says a payer generally issues Form 1099-INT when interest paid reaches $10 or more. It is still reportable if you do not receive the form. Your own tax depends on your situation and on when the interest counts as received. The CD calculator offers an optional modelled tax: it takes a percentage of interest every modelled month. With a hypothetical 22% rate on the one-year example, the model shows $388.07 of net interest instead of the $390.00 you would get by multiplying $500.00 by 78%. The difference exists because tax taken each month leaves less balance to compound. It is an illustration of the effect, not a tax return, and actual timing can differ.

Early withdrawal. The CFPB notes that you generally agree to leave the money in a CD for a set term and that taking it out early means paying a penalty to the bank. Penalties are set by each institution. Many are described as an amount of interest rather than a dollar figure, so the calculator asks you to enter a dollar penalty yourself and does not infer one.

Here is an illustration. Suppose a 36-month CD has a hypothetical penalty equal to 90 days of simple interest using a separate hypothetical 5% penalty-basis rate on $10,000, which is $123.29. This is an example, not a contract standard. What you receive if you leave early:

Figures are rounded from full-precision values, so a row can differ by a cent from subtracting the rounded columns. Until the interest earned exceeds the penalty, which happens here in month 4, leaving early costs part of your principal. A simpler case: a $150 penalty at six months turns the $10,246.95 balance into $10,096.95. Neither figure includes any tax effect. Get the exact penalty rule in writing before you commit, and compare it alongside rate and term, as the CFPB suggests.

How to check your own CD quote

Before you trust a number, run through the same steps as above:

1. Is the rate an APY or a nominal rate? Use the APY if the offer prints one.
2. What is the exact term? Months and days both matter for short CDs.
3. Is interest paid out or left in? The general APY calculation assumes interest remains deposited; required-payout products have special rules. Check whether the balance-growth table applies.
4. What is the penalty, in dollars at the point you might leave? Convert "days of interest" yourself.
5. Are you comparing after tax? Use the same tax assumption on every offer, or none.
6. Does the disclosure match your estimate? Reconcile the term, rate basis, interest-crediting rules and rounding; do not assume a small gap is harmless.

Then calculate your CD's maturity value and compare it with the bank's figure. The calculator models one initial deposit. If you plan to add money regularly, the compound interest calculator handles recurring contributions, and the emergency fund calculator helps you decide how much cash should stay accessible before you lock any of it away. Our emergency fund guide goes through the sizing in more detail.

CD interest questions

Does 5% APY mean I earn 5% in three months?

No. APY is an annual yield. On $10,000, three months at a 5% APY earns about $122.72, not $500. A shorter term earns a fraction of a year of interest, and a little less than the simple fraction because of how compounding is built into the APY.

Can I add money to this CD calculation?

The CD calculator models one deposit that stays untouched until maturity. For regular contributions, use the compound interest calculator. Whether a real CD lets you add money depends on the product terms, so check the agreement.

Is APY the same as the stated interest rate?

Not necessarily. The APY is the effective annual yield after compounding. A stated or nominal rate is quoted before compounding. A nominal 5% compounded monthly has an APY of about 5.116%. Compare APY with APY, and do not compound an APY a second time.

Can a withdrawal penalty reduce my principal?

It can. If the penalty is larger than the interest you have earned so far, you receive less than you deposited. The calculator accepts a dollar penalty that you enter and does not decide what your contract allows, so confirm the rule with the bank.

Sources

• Consumer Financial Protection Bureau, Regulation DD Appendix A: Annual Percentage Yield Calculation: how APY is defined and calculated from the days in the term. Accessed 27 October 2026.
• Consumer Financial Protection Bureau, What is a certificate of deposit (CD)?: terms, early withdrawal penalties and comparing offers; page last reviewed 28 August 2026. Accessed 27 October 2026.
• Internal Revenue Service, Topic no. 403, Interest received: tax treatment of interest, including certificates of deposit; page last reviewed 7 October 2026. Accessed 27 October 2026.