FIRE Calculator Formula
The FIRE number is calculated using the inverse of the Safe Withdrawal Rate (SWR), popularized by the landmark Trinity Study:
At the standard 4% withdrawal rate, the FIRE multiplier is 25x. This means you need 25 times your annual spending to retire indefinitely:
Step-by-Step Example
Suppose your annual expenses are ₹6,00,000, you currently have ₹10,00,000 invested, and you invest ₹30,000/month at 12% annual returns:
- FIRE Number = ₹6,00,000 ÷ 4% = ₹1,50,00,000
- Remaining Corpus Needed = ₹1,50,00,000 − ₹10,00,000 = ₹1,40,00,000
- At ₹30,000/month growing at 12% p.a., this corpus is reached in approximately 12–14 years
Frequently Asked Questions
Your FIRE number is the total investment corpus required to fund your retirement lifestyle indefinitely using passive income. It equals 25x your annual expenses at the 4% withdrawal rate — the standard benchmark from the Trinity Study.
The 4% rule states you can safely withdraw 4% of your portfolio in Year 1 and adjust for inflation annually without depleting it over 30+ years. It is derived from historical US market data and is the most widely used retirement planning benchmark globally.
Lean FIRE — Minimal lifestyle, small corpus (~15-20x expenses). Regular FIRE — Comfortable middle-class lifestyle (25x). Fat FIRE — Luxurious retirement (33-50x). Barista FIRE — Semi-retired with part-time work supplements.