How Much Money Should I Save Each Month to Reach My Goal?

Define the amount and the deadline separately

Write down the full amount required and the date it must be available. For a purchase, include known additional costs such as delivery rather than saving only for the advertised item price. For example, a driveway gravel estimate gives material quantities, while your cash target also needs an actual supplier quote and any delivery charge.

Next, identify the money already allocated to this specific goal. Do not count the same balance toward two goals, or include money you need for expenses before the deadline. The remaining gap is target minus allocated current savings, with no additional saving required if that gap is already zero or negative.

A deadline and a deposit schedule are different inputs. Counting the names of calendar months can overstate the number of contributions you will actually make. List the payment dates that occur after the start date and on or before the deadline.

Calculate monthly savings without interest

Remaining gap = max(0, target − current savings)
Required monthly contribution = remaining gap ÷ deposit count

Suppose your target is $1,200, you already have $200, and your plan starts October 20, 2026. If you deposit monthly on the 20th starting the following month, there are eight deposits through June 27, 2027: November 20 through June 20. With no interest, the remaining $1,000 divided by eight gives $125 per month.

Plan	New deposits	Starting savings	Balance after eight deposits
$100 per month	$800	$200	$1,000
$125 per month	$1,000	$200	$1,200

The $100 plan misses that deadline by $200. Continuing it reaches $1,200 after ten deposits, on August 20, 2027. This is why “time to goal at my current contribution” and “required savings for my deadline” can both be correct while showing different amounts.

The Savings Goal Calculator shows the required deposit prominently when you enter a target date. Your entered monthly amount stays unchanged so you can compare your current plan with the deadline plan. Change that input yourself if you want its timeline to represent the required amount.

Understand the monthly-compounding assumption

For a hypothetical nominal annual rate expressed as a percentage, the calculator divides that rate by 100 and then by 12. Interest is applied to the opening monthly balance before adding the deposit. Deposits occur at the end of each monthly period, on anniversaries of the start date.

Monthly rate r = annual percentage ÷ 100 ÷ 12
Next balance = current balance × (1 + r) + monthly deposit

For a January 31 start, a monthly anniversary falls on February’s last day, then March 31. A chosen deadline between payment dates does not create an additional full monthly deposit. The model does not calculate partial-month interest.

For n monthly periods, initial balance B0, fixed monthly deposit P and nonzero monthly rate r:

Balance = B0 × (1 + r)^n + P × ((1 + r)^n − 1) ÷ r
Required P = max(0, (target − B0 × (1 + r)^n)
                 ÷ (((1 + r)^n − 1) ÷ r))

At zero interest, use the simpler gap-divided-by-deposit-count calculation. Do not divide by a zero rate in the compound formula.

Worked example with assumed interest

Use a $1,000 starting balance, $100 deposits at each monthly period end and a hypothetical 6% nominal annual rate. The monthly rate is 0.5%. After the first period, $1,000 × 1.005 + $100 = $1,105. After the second, $1,105 × 1.005 + $100 = $1,210.525, displayed as $1,210.53.

Of that balance, $1,000 was already saved, $200 is new contributions and $10.525 is estimated interest. Keeping those three components separate prevents attributing your own deposits to investment growth. The example does not round interest to cents each month; a real account’s crediting rules may differ.

A rate is an assumption, not a promised return. A nominal annual rate divided monthly is also not the same input as an effective annual yield. Check the rate convention before using a quoted figure, and allow separately for taxes, fees, changing rates or withdrawals if they affect your plan.

Adjust a deadline that does not fit your budget

Compare the required deposit with the amount left after your actual commitments. If it does not fit, revise the target, extend the deadline, allocate additional existing funds or consider a planned one-time contribution. Do not assume a larger hypothetical return will solve an unaffordable monthly gap.

Recheck the plan when the purchase quote, deadline or contribution changes. With no deposits and no interest, a positive gap never closes. Interest alone can grow a positive balance, but cannot grow a zero balance in this model. The calculator stops projections after 100 years; a horizon warning is not a promise that waiting longer is practical.