Full explanation
FIRE number = Annual expenses × 25. Based on the 4% safe withdrawal rate: if your corpus is 25x annual expenses, you can withdraw 4% per year indefinitely (in theory). Example: Annual expenses ₹12 lakh → FIRE number = ₹3 crore. With inflation: those ₹12 lakh today will be more in nominal terms by retirement. Calculate future expenses by inflating forward: ₹12 lakh × (1.06)^20 = ₹38.5 lakh annual in 20 years → corpus needed = ₹38.5L × 25 = ₹9.6 crore. Track progress: FIRE % = current corpus / FIRE number × 100. At 100%, you're FI.