What is the Savings Monthly Deposit Calculator?
This calculator tells you how much you need to deposit each month to reach a specific savings goal by a target date, given an annual interest rate compounded monthly. It is ideal for planning a down payment, emergency fund, vacation, or any future lump sum.
How to use it
Enter your savings goal (the future value you want), the annual interest rate your account earns, and the number of years until you need the money. The tool returns the required monthly deposit plus a breakdown of how much comes from your own contributions versus interest.
The formula explained
The calculation is the standard sinking-fund (ordinary annuity) formula:
$$\text{PMT} = \text{FV} \times \frac{r/12}{(1 + r/12)^{12t} - 1}$$Here FV is the goal, \(r\) is the annual rate as a decimal, \(t\) is years, and \(12t\) is the number of monthly deposits. Deposits are assumed to be made at the end of each month (ordinary annuity). If the rate is zero, the formula reduces to FV divided by the number of months.
Worked example
Goal $50,000, rate 5%, 10 years. Here \(r/12 = 0.0041667\) and \(12t = 120\). \((1.0041667)^{120} \approx 1.647009\), so the denominator is \(0.647009\). $$\text{PMT} = 50{,}000 \times \frac{0.0041667}{0.647009} \approx \$321.99$$ per month. Total deposited = \(321.99 \times 120 \approx \$38{,}639\), and interest earned \(\approx \$11{,}361\).
FAQ
Does this assume end-of-month deposits? Yes — it uses the ordinary annuity convention. If you deposit at the start of each month, you'd need slightly less.
Is the rate compounded monthly? Yes, the annual rate is divided by 12 and applied each month.
What if my rate is 0%? The calculator simply divides your goal evenly across all the months.
