How this calculator works
Interest is applied monthly, followed by the month-end contribution. The result is the first whole month whose ending balance meets the goal. The last full contribution can push the balance above the target. Projections stop at 1,200 months and exclude fees, tax and changing rates.
The formula
Next balance = Current balance × (1 + annual rate / 1200) + monthly deposit
Repeat until balance reaches the goal.
Interest earned = final balance − starting savings − new deposits.A quick example
With a goal of 10,000, current savings of 4,000 and deposits of 500 per month at 0% interest, the target is reached in 12 months with 10,000 total deposits.
How to use this calculator
- Enter your target and current savings.
- Set the monthly deposit and assumed annual nominal rate.
- Calculate whole months to the target and review the projected balance.
A few common questions
What if I have already reached my goal?
The result is zero months and no new interest or contributions.
Can interest alone reach the target?
Yes, if existing savings and a positive rate are sufficient within the 100-year calculation limit.
What if I save nothing and earn no interest?
A target above your current savings is unreachable under those assumptions; the calculator explains this.