Savings Goal Calculator

The formula

Your current savings grow to S × (1 + i)^m. The shortfall to the goal is G − S × (1 + i)^m, and each monthly deposit adds ((1 + i)^m − 1) ÷ i by the deadline, so the monthly amount is the shortfall divided by that factor. Here i is the annual rate ÷ 12 and m is the number of months. With 0% interest this reduces to (G − S) ÷ m.

Worked example

Goal 25,000 in 4 years with 5,000 already saved at 4%. The 5,000 grows to 5,865.99, leaving 19,134.01 to build from deposits. Over 48 months at 4% that needs 368.25 a month. With no interest and no starting savings, a goal of 12,000 in 5 years is simply 200 a month.

Limitations

It assumes a constant interest rate and equal monthly deposits, and ignores taxes and inflation. If the cost of your goal will rise with inflation, enter a higher target.

How the interest rate changes the monthly amount

Using the same goal of 25,000 in 4 years with 5,000 already saved and deposits at the end of each month: with no interest you must save 416.67 a month, at 4% it falls to 368.25, and at 6% to 344.70. A higher rate does more of the work, so you deposit less.

Start of the month or the end

Depositing at the start of each month earns one extra month of interest on every payment. At 4% that trims the monthly amount from 368.25 to 367.02, a difference of 1.23, so the timing matters far less than the rate or the deadline.

When your savings already cover the goal

If what you have saved, growing at the rate you enter, reaches the goal before the deadline without any deposits, the calculator shows a monthly amount of 0 and a short note instead of a negative figure.

Monthly saving, step by step

To reach 20,000 in 3 years with 2,000 already saved and 5% a year, you need to put away 456.14 a month if deposits are made at the end of each month, of which 1,578.86 of the final balance is interest. Depositing at the start of each month lowers that to 454.25. With a rate of 0% the answer is exactly 500.00 a month.

If your current savings alone will reach the goal, the tool shows 0.00 and a note saying so, instead of a negative amount. A goal of 1,000 with 2,000 already saved is an example.