How do I calculate how much to save each month for a goal?

Work backwards from the goal. With a rate of i per month, N months, a starting balance S and a goal G, the level deposit is PMT = (G − S(1+i)^N) × i ÷ ((1+i)^N − 1). For $10,000.00 from $1,000.00 at 4.5% APY over 36 months, i = 0.367481% and the deposit is $230.62. The calculator gets the same answer by running the real schedule, so rounding to the cent is exact.

Why is the final deposit different?

Deposits are whole cents, and $230.62 is the smallest level amount that gets there in time, so by the last month you need slightly less: $230.24 in the example. The last deposit is trimmed so the balance equals the goal exactly instead of overshooting by a few cents.

How is the APY turned into a monthly, biweekly or weekly rate?

APY already includes compounding, so the rate for one period is (1 + APY)^(1/k) − 1, where k is 12 for monthly, 26 for every two weeks and 52 for weekly deposits. 4.5% APY is 0.367481% per month, 0.169439% every two weeks and 0.084684% per week. Dividing the APY by 12 would slightly understate it. A nominal rate (APR) is different: convert it to an APY first.

When are deposits made?

At the end of each period, after that period’s interest is added. The first deposit is one period after the start date, and monthly dates keep the start date’s day of the month (moved back to the last day in shorter months). A deposit made at the start of a period would earn one extra period of interest, so real savings made earlier than assumed come out a little ahead.

How does it handle a 0% interest rate?

Interest is zero every period, so the deposit is the remaining amount divided by the number of deposits, rounded up to the next cent, with a smaller last deposit. In the example at 0% APY you would deposit $250.00 a month and earn $0.00, against $230.62 and $698.06 at 4.5%.

What if I have already reached my goal?

The calculator says so and shows nothing left to save. For example, a starting balance of $10,500.00 against a $10,000.00 goal gives “You have already reached your goal”. If your balance would reach the goal on interest alone, it reports that no deposits are needed.

What makes a goal impossible?

Three things: no deposit and no interest, so the balance never grows; a deposit so small that reaching the goal would take more than 100 years; and a deadline with no deposit date before it (for example a target only days after the start with monthly deposits). The calculator explains which one applies instead of giving a number.

How does this relate to the compound interest calculator?

They are the same math in opposite directions. The compound interest calculator takes a deposit and shows the final balance; this one takes the final balance and shows the deposit. Put $230.62 a month into the compound interest calculator with a $1,000.00 start, 4.5% compounded annually (that makes the rate an APY), 3 years and deposits at the end of the month, and you land on $10,000.00, within the few cents the trimmed final deposit accounts for.

Does it account for taxes, fees or changing rates?

No. It assumes one fixed APY for the whole period. Savings accounts and CDs change rates, interest may be taxable, and inflation reduces what the goal will buy, so treat the result as a planning estimate, not financial advice.

Is anything I type stored or sent?

No. The calculation runs in your browser and nothing you enter leaves your device.

Savings Goal Calculator

To grow $1,000.00 to $10,000.00 in 36 months at 4.5% APY, save $230.62 at the end of each month: $8,301.94 of deposits plus $698.06 of interest, reaching the goal on January 1, 2029 when the final deposit is trimmed to $230.24 so the balance lands on $10,000.00 to the cent. Enter your goal, what you have now, the annual interest rate (APY) and a start date, then choose a date or a number of months to find the deposit per month, every two weeks or week. Or switch to a fixed deposit to see how long it takes and when you will get there. It builds the schedule one period at a time, rounding the interest to the cent each time, and shows total deposited against interest earned plus a year-by-year table. This is an estimate for planning, not financial advice.

Updated 2026-10-16Runs in your browser: nothing you enter is uploadedHow this tool works

Save $230.62 each month

To reach $10,000.00 on January 1, 2029: $8,301.94 deposited plus $698.06 interest on top of your $1,000.00 start.

Deposit each month: $230.62
Number of deposits: 36
Final deposit (adjusted): $230.24
Goal date: January 1, 2029
Starting balance: $1,000.00
Total deposited: $8,301.94
Interest earned: $698.06
Final balance: $10,000.00
Effective rate per month: 0.367481%

An estimate for planning, not financial advice.

Year-by-year savings

Each row covers 12 months from the start date; the last row ends on the goal date. Deposits and interest are for that year only.

Year	Last deposit	Deposited	Interest	Balance
1	January 1, 2027	$2,767.44	$101.63	$3,869.07
2	January 1, 2028	$2,767.44	$230.76	$6,867.27
3	January 1, 2029	$2,767.06	$365.67	$10,000.00

Monthly deposit needed to save $10,000.00 from nothing at 4.5% APY

Deposits at the end of each month, interest rounded to the cent every month. Longer horizons let interest do more of the work.
Time	Monthly deposit	Total deposited	Interest earned
1 year	$816.63	$9,799.49	$200.51
2 years	$399.33	$9,583.85	$416.15
3 years	$260.32	$9,371.42	$628.58
5 years	$149.28	$8,956.26	$1,043.74
10 years	$66.46	$7,974.52	$2,025.48

How long $10,000.00 takes from $1,000.00 at 4.5% APY

A fixed deposit at the end of each month. The last deposit is smaller, so the balance lands exactly on the goal.
Monthly deposit	Deposits needed	Time to goal	Interest earned
$100.00	76	6 years 4 months	$1,470.50
$200.00	42	3 years 6 months	$831.52
$300.00	29	2 years 5 months	$574.98
$500.00	18	1 year 6 months	$354.94
$1,000.00	9	9 months	$166.98

What the interest rate changes in the example ($1,000.00 to $10,000.00 in 36 months)

Same goal, start and time; only the APY changes.
APY	Monthly deposit	Total deposited	Interest earned
0%	$250.00	$9,000.00	$0.00
1%	$245.56	$8,840.16	$159.84
2%	$241.20	$8,683.04	$316.96
4.5%	$230.62	$8,301.94	$698.06
5%	$228.55	$8,227.73	$772.27
7%	$220.47	$7,936.87	$1,063.13

Deposit frequency in the example

$1,000.00 to $10,000.00 within 36 months of the start date at 4.5% APY.
Frequency	Deposit	Number of deposits	Interest earned
Monthly	$230.62	36	$698.06
Every two weeks	$106.34	78	$706.25
Weekly	$53.15	156	$709.87

How to work out how much to save to reach a savings goal

Enter the goal and what you have. Type the amount you want to reach ($10,000.00 in the example) and your starting balance ($1,000.00; it can be 0).
Enter the interest rate as an APY. Use the annual percentage yield your account advertises, such as 4.5. Enter 0 for an account that pays no interest.
Choose how often you deposit and when you start. Pick monthly, every two weeks or weekly, and set the start date. The first deposit is one period after it.
Pick the deadline. Choose a number of months (36 in the example) or a target date. The calculator counts how many deposit dates fit before it.
Read the deposit. The example needs $230.62 per month, with a final deposit of $230.24. The year-by-year table shows what you deposit and earn each year.
Or find the time for a fixed deposit. Switch to “How long will a fixed deposit take?” and enter what you can afford. With $250.00 a month the example reaches $10,000.00 on November 1, 2028.

Frequently asked questions

How do I calculate how much to save each month for a goal?: Work backwards from the goal. With a rate of i per month, N months, a starting balance S and a goal G, the level deposit is PMT = (G − S(1+i)^N) × i ÷ ((1+i)^N − 1). For $10,000.00 from $1,000.00 at 4.5% APY over 36 months, i = 0.367481% and the deposit is $230.62. The calculator gets the same answer by running the real schedule, so rounding to the cent is exact.
Why is the final deposit different?: Deposits are whole cents, and $230.62 is the smallest level amount that gets there in time, so by the last month you need slightly less: $230.24 in the example. The last deposit is trimmed so the balance equals the goal exactly instead of overshooting by a few cents.
How is the APY turned into a monthly, biweekly or weekly rate?: APY already includes compounding, so the rate for one period is (1 + APY)^(1/k) − 1, where k is 12 for monthly, 26 for every two weeks and 52 for weekly deposits. 4.5% APY is 0.367481% per month, 0.169439% every two weeks and 0.084684% per week. Dividing the APY by 12 would slightly understate it. A nominal rate (APR) is different: convert it to an APY first.
When are deposits made?: At the end of each period, after that period’s interest is added. The first deposit is one period after the start date, and monthly dates keep the start date’s day of the month (moved back to the last day in shorter months). A deposit made at the start of a period would earn one extra period of interest, so real savings made earlier than assumed come out a little ahead.
How does it handle a 0% interest rate?: Interest is zero every period, so the deposit is the remaining amount divided by the number of deposits, rounded up to the next cent, with a smaller last deposit. In the example at 0% APY you would deposit $250.00 a month and earn $0.00, against $230.62 and $698.06 at 4.5%.
What if I have already reached my goal?: The calculator says so and shows nothing left to save. For example, a starting balance of $10,500.00 against a $10,000.00 goal gives “You have already reached your goal”. If your balance would reach the goal on interest alone, it reports that no deposits are needed.
What makes a goal impossible?: Three things: no deposit and no interest, so the balance never grows; a deposit so small that reaching the goal would take more than 100 years; and a deadline with no deposit date before it (for example a target only days after the start with monthly deposits). The calculator explains which one applies instead of giving a number.
How does this relate to the compound interest calculator?: They are the same math in opposite directions. The compound interest calculator takes a deposit and shows the final balance; this one takes the final balance and shows the deposit. Put $230.62 a month into the compound interest calculator with a $1,000.00 start, 4.5% compounded annually (that makes the rate an APY), 3 years and deposits at the end of the month, and you land on $10,000.00, within the few cents the trimmed final deposit accounts for.
Does it account for taxes, fees or changing rates?: No. It assumes one fixed APY for the whole period. Savings accounts and CDs change rates, interest may be taxable, and inflation reduces what the goal will buy, so treat the result as a planning estimate, not financial advice.
Is anything I type stored or sent?: No. The calculation runs in your browser and nothing you enter leaves your device.

How it works

Everything is counted in whole cents. The rate for one deposit period is (1 + APY)^(1/k) − 1 with k = 12, 26 or 52 periods a year, so a year of periods compounds back to exactly the APY; for monthly deposits this is the compound interest calculator’s own effective monthly rate for annual compounding. Each period the balance earns interest equal to balance × rate, rounded to the nearest cent, and then the deposit is added, i.e. deposits are at the end of the period and the first one is a full period after the start date. When the deposit would take the balance past the goal, only what is needed is deposited, so the balance equals the goal exactly. To find the deposit for a deadline the calculator searches for the smallest whole-cent deposit whose schedule reaches the goal within the deposit dates available, which agrees with the annuity formula PMT = (G − S(1+i)^N) × i ÷ ((1+i)^N − 1) to within a few cents and is exact for the rounding it models. Deposit dates are the start date plus whole months (monthly, clamped to the end of shorter months), 14 days or 7 days; a target date counts the dates on or before it, and “months” means that many months after the start date. The year-by-year table groups periods into 12-month spans from the start date. Real accounts may credit interest daily, compound differently, change rates or pay on different dates, so figures can differ slightly from a statement. Taxes, fees and inflation are not modelled. This is an estimate for planning and not financial advice. Everything runs in your browser and nothing you type is sent anywhere.

Sources

All tools Home & DIY calculators