Estimate the monthly contribution needed to reach a savings target.
It turns the values and assumptions you choose into a transparent planning result. It does not import financial accounts, guess missing household information, or decide what is suitable for you.
The relationship
Follow the money, rate, and time basis
With end-of-month contributions, target = current savings × (1+r)^n + contribution × ((1+r)^n−1)/r, using the n-month zero-rate limit when r = 0.
Visual explanation
What the calculation is doing
Today
Targetgap + contribution pathWith end-of-month contributions, target = current savings × (1+r)^n + contribution × ((1+r)^n−1)/r, using the n-month zero-rate limit when r = 0.
Read the result
Keep the result inside its assumptions
A 12,000 target from zero current savings over 12 months at 0% requires 1,000 at the end of each month.
Contributions occur at each month-end and the entered nominal annual return is divided by 12. Actual savings or investment returns, fees, taxes, and timing can differ.
Quick guide
How to use this calculator
Enter one scenario using a consistent currency and the periods shown by each label.
Keep targets, coverage time, income basis, and expected return aligned with your own planning definition.
Read the result with the visible assumptions before using it in a financial decision.
Calculation method
Calculation method
With end-of-month contributions, target = current savings × (1+r)^n + contribution × ((1+r)^n−1)/r, using the n-month zero-rate limit when r = 0.
Exact decimal/rational arithmetic is used for cash-flow totals. The savings-goal projection uses stable logarithmic compounding with a zero-rate limit and rejects overflow or a nonzero result that would become zero. Repeating ratios use parentheses; an ellipsis marks a preview longer than 12 decimal places.
Worked example
Worked example
A 12,000 target from zero current savings over 12 months at 0% requires 1,000 at the end of each month.
With end-of-month contributions, target = current savings × (1+r)^n + contribution × ((1+r)^n−1)/r, using the n-month zero-rate limit when r = 0.
Supported inputs
Precision and limits
Visible input limits
Amounts accept up to 30 digits and 12 decimal places and are capped at 1e12. Rates are capped at 1000%; whole-month horizons are capped at 1,200, with 120 months for reserve coverage and sabbatical duration.
International scope
No currency, country, benefit system, recommended fund size, guaranteed return, or savings-rate standard is assumed.
Planning boundary
Results are deterministic projections of entered assumptions, not guarantees, investment advice, or a judgment about an adequate reserve.
Calculator-specific assumptions
Contributions occur at each month-end and the entered nominal annual return is divided by 12. Actual savings or investment returns, fees, taxes, and timing can differ.
