Monthly savings for a goal
Solve for equal end-of-month deposits with monthly compounding.
How this works
Let G be the target, P current savings, i = assumed annual percentage return/1200 and n the number of months. Required end-of-month contribution C = max(0, [G − P(1+i)^n] ÷ [((1+i)^n − 1)/i]). At 0% return, C = max(0, [G − P]/n). Contributions and growth are applied monthly.
Example
The illustration may use different inputs from the reproducible default inputs listed below.
With the defaults, n = 36 months and i = 4/1200. Subtract the projected growth of the existing $5,000 from the $20,000 target, then divide by the 36-month deposit-growth factor. With all reset-default inputs, required end-of-month contribution: $376.19.
- Target savings ($)
- 20000
- Already saved ($)
- 5000
- Assumed annual return (%)
- 4
- Months until goal
- 36
- Required end-of-month contribution
- $376.19
Scope and assumptions
Uses a constant nonnegative nominal return and equal end-of-month deposits. Taxes, fees, withdrawals and investment losses are excluded. If projected growth of current savings already meets the target, the required contribution is zero. Returns are assumptions, not guarantees.
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