Calculator Panel
Calculation Ready
Enter your values above and click Calculate.
What This Calculator Does
This calculator evaluates your active savings trajectory, identifies any monthly shortfall relative to your goal, and shows exactly how much more you need to save to stay on track.
How to Use This Calculator
Enter target nest egg, years to retirement, current savings, current monthly savings, and expected growth rate. Click Calculate to see your monthly savings gap.
How the Calculation Works
The underlying math engine processes your inputs using exact formulas. This systematic approach ensures professional, institutional-grade calculation precision:
Mathematical Formula
Formula Legend:
- · Target = Target retirement nest egg value.
- · Current = Current savings balance.
- · r = Monthly interest rate (annual / 12).
- · t = Total months to target age.
Practical Example
You want a target nest egg of $1,500,000 in 20 years. You have $100,000 starting, earn 6.0% real growth, and currently save $1,200 monthly:
Step-by-Step Mathematical Walkthrough:
- 1 Target = $1,500,000. Years = 20 (240 months).
- 2 At 6.0% return, your current $100,000 grows to $331,020.
- 3 Remaining amount to accumulate from savings = $1,168,980.
- 4 Required monthly savings to hit this is $2,525.07.
- 5 Your current savings are $1,200 monthly.
- 6 Your monthly FIRE Savings Gap is $1,325.07 ($2,525.07 - $1,200).
Important Assumptions & Notes
- All dollar values are in real (inflation-adjusted) terms.
- Monthly savings are added at the start of each month.
Common Mistakes or Considerations
- Ignoring the savings gap and hoping high investment returns will compensate, which can result in missing your target retirement date.
- Setting an unrealistic savings goal that exceeds your monthly take-home income.
Frequently Asked Questions
What is a savings gap?
A savings gap is the difference between what you are currently saving each month and the amount you must save to successfully accumulate your target retirement portfolio in your desired timeline.
How do I close my FIRE Savings Gap?
You can close the gap by increasing your monthly savings, extending your retirement timeline (working longer), lowering your retirement expenses, or optimizing your portfolio for slightly higher returns.
How does compound interest affect the savings gap?
The longer your timeline, the smaller your monthly gap will be, because compound interest does more of the heavy lifting. Start early to keep the gap small.
Can investment returns alone close a savings gap?
While high returns help, they carry substantial downside risk. Increasing your savings rate is a much more reliable and controllable way to close the gap.
What is a healthy FIRE savings rate?
Most members of the FIRE community aim for a savings rate of 40% to 65% of their net household income.