Turn a target into a monthly amount
Work backward from a target balance to find an equal monthly deposit. Compare what you put in with the interest added under a fixed monthly compounding model.
Required monthly deposit
Enter a target, current savings, time, and rate, then select Calculate.
The deposit is rounded upward to 0.01; other amounts are displayed to two decimal places. These are model results, not a guaranteed return. Calculations run in your browser. Press Enter to calculate. Successful results appear in this tab's Recent calculations.
(10,000 − 1,000) ÷ 12 = 750
Starting with 1,000 and an assumed rate of 0%, deposit 750.00 each month. The 12 new deposits total 9,000.00, bringing the final balance to exactly 10,000.00. Deposit timing makes no difference at a zero rate.
100 ÷ 3 = 33.333… → 33.34
Starting from zero, three deposits of 33.33 would leave the balance at 99.99. Using 33.34 each time produces 100.02, a surplus of 0.02. The final deposit remains the same size in this tool.
End: 202 ÷ 2.01 → 100.50
With no starting savings, a 12% nominal annual rate gives 1% per month. Month-end deposits require 100.50 each, with a projected balance of approximately 202.01. Month-beginning deposits require 99.51 each and project approximately 202.02 because both deposits earn an additional month of interest.
Let T be the target balance, P the current savings, N the number of months, R the nominal annual rate entered as a percentage, and D the equal monthly deposit. Set r = R ÷ 1,200 and G = (1 + r)N.
Final balance = P × G + D × A
For month-end deposits, A = (G − 1) ÷ r when r is positive. At r = 0, use A = N. For month-beginning deposits, multiply A by (1 + r). Solve for the deposit using D = max(0, (T − P × G) ÷ A).
The calculated deposit is increased to the smallest multiple of 0.01 that reaches the target. The final balance, total new deposits, interest, and surplus are then calculated using this rounded-up deposit. Interest equals the final balance minus the original savings and all new deposits. Surplus equals the final balance minus the target; it can include growth already supplied by the original savings.
All calculations retain exact integer fractions with no monthly interest rounding. Other displayed amounts use two decimal places, with halfway values rounded away from zero. ≈ identifies display rounding. A notice appears if a positive amount rounds to 0.00. The monthly deposit itself never rounds down to zero when a positive contribution is needed.
Inputs accept up to 64 characters, 15 integer digits, and 10 decimal places. Months must be a whole number from 1 to 1,200. The annual rate must be between 0% and 100%; this range is a calculation limit, not an expected savings return. All amounts share the same currency, which must use 0.01 increments for deposits. The tool does not convert currencies.
The rate stays constant and compounds monthly. There are no withdrawals, missed deposits, fees, taxes, inflation adjustments, changing rates, or daily account rules. Actual providers may round interest or apply deposit cutoffs differently. A projected balance above the target is conditional on these assumptions, not a promise about an investment or account.
Reference: OpenStax — Methods of Savings explains future values from an initial deposit and regular deposits, including deposits at the end or beginning of each compounding period.
Your current savings, including the assumed interest over the period, already reach or exceed the target. The monthly deposit is therefore 0.00. This can happen even if your current balance is below the target today. Check the rate and time assumptions before relying on that projection.
No. This model divides the nominal annual rate by 12 to get the monthly rate. An effective annual yield includes compounding. For example, a nominal 12% rate compounded monthly corresponds to (1.01)12 − 1, approximately 12.68% effective annual growth. Do not copy an APY into this field as if it were a nominal rate.
Choose Beginning of each month if the first new deposit happens immediately. Choose End of each month if it happens after one month. Both choices include exactly the entered number of deposits and measure the balance at the end of the final month.
Rounding the monthly deposit upward to 0.01 can create a small surplus. That extra amount can also earn interest. The tool keeps every deposit equal, including the last one, rather than reducing the final deposit. A larger surplus may mean the original savings would already exceed the goal without new deposits.
You can compare an amount and a whole-month deadline. A zero-rate calculation shows how much must come from your own deposits when no interest is assumed. The calculator does not choose an account, predict a rate, or assess whether a monthly amount is affordable.