How Much Money Do You Need to Retire? The 4% Rule & FIRE Number Explained

A mathematical roadmap to financial freedom: determine how large your investment portfolio must be to fund your living expenses indefinitely.

By AnyCalcHub Wealth Research

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1. The 25x Rule & 4% Safe Withdrawal Rate

Based on the historical Trinity Study, a portfolio diversified across equities and bonds can support a 4% annual withdrawal adjusted for inflation over a 30-year retirement without depleting.

Mathematical Formula

FIRE Corpus = Annual Living Expenses × 25
Safe Annual Withdrawal = Total Corpus × 0.04

Step-by-Step Worked Example

Monthly Expenses₹100,000

Annual Expenses₹1,200,000

Step 1:Multiply annual expenses by 25: 1,200,000 × 25 = ₹30,000,000

Step 2:Verify at 4% withdrawal: 30,000,000 × 0.04 = ₹1,200,000/yr

Final Result: Required Retirement Corpus: ₹3.0 Crore

Frequently Asked Questions

Common questions and mathematical nuances for this calculation.

What is the difference between Lean FIRE and Fat FIRE?

Lean FIRE targets covering bare essential subsistence expenses (e.g. 20x to 25x modest spend), while Fat FIRE accommodates luxury lifestyle, travel, and discretionary spending (often 30x to 40x annual expenses).

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