High-Yield Savings & CD Calculator

See how a high-yield savings account or CD grows from your deposit, optional monthly deposits and the APY your bank quotes.

Results

Enter your numbers to see the results.

Estimate only, not savings, tax or investment advice. Enter the APY your bank quotes; this page does not list current rates, and those rates can change. APY already includes compounding, so the tool does not ask how often interest is credited. Monthly interest is rounded half-up to the cent (bank-style monthly credit), so 12 months at 4.00% APY on $10,000 shows $400.01 of interest, not exactly $400.00. CD early-withdrawal penalties and account fees are not included.

Last reviewed: November 11, 2026

A high-yield savings account and a certificate of deposit both grow from the APY the bank quotes, but they don’t behave the same way. A savings account can take monthly deposits; a CD generally does not. Enter an opening deposit, the APY, and a term in months (or years — 1 year is 12 months). In savings mode you can add a monthly deposit at the start or end of each month. You’ll get the ending balance, total deposits, interest earned, and a yearly table of deposits, interest and balance. Savings mode also shows what the same deposits would be worth in a plain 0% account, which is simply the money you put in.

How to use it

Choose Savings account or CD. CD mode hides the monthly deposit field, because a typical CD does not take added deposits during the term.
Enter the opening deposit. In savings mode, you can also enter a monthly deposit. At least one of those two amounts must be greater than $0.00.
In savings mode, choose when each monthly deposit is added: end of the month (the default) or start of the month.
Enter the APY your bank is quoting, not a rate from a comparison table on this site — we don’t publish one.
Enter the term in months, up to 600 (50 years). A years helper treats 1 year as 12 months. The default term is 12 months.
Read the ending balance, total deposits, interest earned, the yearly table, and — in savings mode — the 0% comparison line.

How it works

The monthly rate is taken from the APY so that 12 months of that rate equal the quoted annual yield, before cent rounding: monthly rate r = (1 + APY)^(1/12) − 1, with APY as a fraction. At 0% APY, r is 0 and the balance is just the deposits.
Each month, if timing is start of the month, the monthly deposit is added first.
Interest for the month = current balance × r, rounded half-up to the cent, then added to the balance.
If timing is end of the month, the monthly deposit is added after that interest credit.
Total interest is the sum of those rounded monthly credits. Ending balance = total deposits + total interest.
Because rounding happens each month, a 4.00% APY does not always produce a number that lands on an exact 4.00% of the opening deposit. The $10,000, 12-month CD in the first example earns $400.01, and the page footnote explains that this is expected.
Opening deposit and monthly deposit cannot both be $0.00: “Enter a deposit.” Empty or non-numeric fields show no result, not NaN.

Worked examples

A one-year CD at 4.00% APY (case 1).

$10,000, 4.00% APY, 12 months, no monthly deposits. The ending balance is $10,400.01. Interest earned is $400.01. Total deposits stay $10,000.00. The same path with start-of-month timing (the extra printed row in verify_wave4) is unchanged, because there is no monthly deposit to time.

A high-yield savings account with monthly deposits (case 2).

$5,000 opening plus $200 at the end of each month, 4.25% APY, 24 months. Total deposits are $9,800.00. Interest is $630.83. The ending balance is $10,430.83. A 0% account with the same deposits would show $9,800.00.

Building a balance from monthly deposits only (case 3).

$0 opening plus $500 at the end of each month, 4.50% APY, 60 months. Total deposits are $30,000.00. Interest is $3,495.85. The ending balance is $33,495.85.

A six-month CD (case 4).

$25,000 at 5.00% APY for 6 months. Interest is $617.36. The ending balance is $25,617.36.

A 0% savings path (case 5).

$1,000 opening plus $100 a month, 0% APY, 12 months. Interest is $0.00. The ending balance equals the deposits: $2,200.00.

Start-of-month deposits (case 6).

$2,000 opening plus $150 at the start of each month, 3.80% APY, 36 months. Total deposits are $7,400.00. Interest is $559.34. The ending balance is $7,959.34. Adding the deposit before interest is credited gives that month’s new money a month of yield.

Results at a glance

Results at a glance
Example	Path	Deposits	Interest	Ending balance
$10,000, 4.00% APY, 12 months	CD	$10,000.00	$400.01	$10,400.01
$5,000 + $200/mo (end), 4.25%, 24 months	Savings	$9,800.00	$630.83	$10,430.83
$0 + $500/mo (end), 4.50%, 60 months	Savings	$30,000.00	$3,495.85	$33,495.85
$25,000, 5.00% APY, 6 months	CD	$25,000.00	$617.36	$25,617.36
$1,000 + $100/mo, 0% APY, 12 months	Savings	$2,200.00	$0.00	$2,200.00
$2,000 + $150/mo (start), 3.80%, 36 months	Savings	$7,400.00	$559.34	$7,959.34

FAQ

How much interest would $10,000 earn in a high-yield savings account or CD?

It depends on the APY and the term, and on whether you add monthly deposits. In the one-year CD example, $10,000 at 4.00% APY grows to $10,400.01, so the interest is $400.01. That figure is a monthly credit rounded to the cent, which is why it is one cent above a flat 4.00% of $10,000.

Does this calculator use APY or APR?

It uses the APY you type. APY already includes compounding, so the tool does not ask how often the bank compounds interest. The monthly rate is the twelfth-root of (1 + APY), and each month’s interest is rounded half-up to the cent.

Can I include monthly deposits?

Yes, in savings-account mode. Choose whether each deposit is added at the start or the end of the month. CD mode hides that field. Case 2 ($5,000 plus $200 a month at 4.25% for two years) ends at $10,430.83.

Why doesn’t a 4.00% APY on $10,000 come out to exactly $400.00?

Interest is credited monthly and rounded half-up to the cent each month. Over 12 months those rounded credits total $400.01 in the first example. The page footnote calls this out so it isn’t mistaken for an error.

Do you show current high-yield or CD rates?

No. Rates change, and this tool has no rate feed. Paste the APY from your bank’s quote or account details. The same math works for any bank that quotes an APY; we don’t rank or endorse institutions.

What happens at 0% APY?

There is no interest. The ending balance equals the money you deposited, as in the $1,000 plus $100 a month example, which ends at $2,200.00.

Is this the same as a compound interest or savings-goal calculator?

It projects a balance from deposits and a quoted APY, including a CD mode. A separate savings-goal mode is not on this page. If a goal amount is added later, it belongs here rather than on a second, overlapping tool.