FIRE Calculator
Achieving FIRE (Financial Independence, Retire Early) is a math problem involving your savings rate and investment returns. It occurs at the “Crossover Point”—the moment your investment income exceeds your annual expenses.
This calculator determines your FIRE Number based on the 4% rule and calculates your Coast FIRE Age—the age at which you can stop saving completely and let compound interest finish the job.
Financial Details
InputIndependence Timeline
ProjectionsUnderstanding the FIRE Formulas
The FIRE movement relies on two main mathematical principles: the Rule of 25 for determining your target, and Compound Interest for determining your timeline.
1. The FIRE Number Formula
Based on the Trinity Study, withdrawing 4% of your portfolio annually is considered “safe” for a 30-year retirement.
Target = Annual Spending × 25Example: If you spend $40,000/year, you need $1,000,000 invested.
2. What is Coast FIRE?
Coast FIRE is a financial milestone where you have invested enough money that, without contributing another penny, your portfolio will grow to your FIRE Number by traditional retirement age (e.g., 65) simply through compound interest.
Once you reach Coast FIRE, you only need to work enough to cover your current annual expenses, giving you massive freedom to switch careers or work part-time.
3. Types of FIRE
- Lean FIRE: Retirement with a minimalist budget (e.g., <$40k/year expenses).
- Fat FIRE: Retirement with a luxurious budget (e.g., >$100k/year expenses). Requires a larger nest egg.
- Barista FIRE: Retiring from a high-stress career to a lower-stress, part-time job that covers bills while your investments grow.
4. Why Use Real Rate of Return?
Stock markets might return 10% on average, but inflation eats away purchasing power (avg 3%). This calculator uses a default 7% Real Return (10% growth – 3% inflation) to keep all numbers in “Today’s Dollars,” making it easier to visualize your future buying power.