How to use this calculator
A monthly savings plan combines a starting amount, regular deposits, and an assumed return. Future-balance mode projects what those inputs may produce. Target mode rearranges the same equation to calculate the monthly deposit needed to reach an ending goal under the chosen assumptions.
The method
Enter the values in the labeled fields, check the units or selected mode, and choose Calculate. The result includes the applicable working and a breakdown or visual when useful. Change an input and calculate again to update the result.
Calculation goal: Project my future balance Starting balance ($): 10000 Monthly contribution ($): 250 Assumed annual effective return (%): 5 Years: 10
Projected savings balance: $54,879.74
Hypothetical projection over 10 years.
Scope and limitations
Effective annual return is converted to a monthly equivalent, with end-of-month deposits. No tax, fee, inflation, or market-variability model. A zero-rate case is handled separately without division by zero.
Common questions
Are deposits made at the beginning or end of the month?
At the end of each month, after that month's modeled growth.
Why does target mode sometimes show a zero deposit?
The starting balance alone already reaches or exceeds the target under the chosen assumptions.
References & further reading
External references provide background, not an endorsement of this implementation. See our methodology for numerical conventions and limitations.