Foundations of Financial Independence and Early Retirement (FIRE)

The Financial Independence, Retire Early movement has attracted millions of followers precisely because it challenges the assumption that work until sixty-five is inevitable. But the FIRE framework rests on specific mathematical and behavioral foundations that are worth understanding clearly before committing to its demands. What savings rate is actually required? How does the 4% rule work and what are its limits? What distinguishes lean, fat, and coast FIRE? This course answers those questions rigorously. By the end of this course you will be able to explain the relationship between savings rate and years-to-independence, describe how the 4% rule was derived and what assumptions it makes, distinguish between the major FIRE variants, and identify the lifestyle and behavioral commitments that underpin any FIRE strategy. What you will learn: - The savings rate equation: how the percentage of income saved, not the absolute dollar amount, determines years to financial independence - The 4% rule: its historical derivation from safe withdrawal rate research, its assumptions, and the conditions under which it may be too aggressive or too conservative - Lean FIRE: targeting a lower annual spending level to reduce the required portfolio size, and the trade-offs this entails - Fat FIRE: maintaining a higher lifestyle standard in early retirement and what portfolio size that requires - Coast FIRE: the concept of saving enough early that compounding alone will fund traditional retirement without further contributions - Barista FIRE and semi-retirement: how partial income from meaningful work changes the required portfolio size - The sequence-of-returns risk: why a market downturn in the first years of early retirement is especially damaging and how FIRE practitioners think about managing it - The behavioral and psychological dimensions: what early retirement actually involves day-to-day and the common challenges people underestimate The course is organized as five reading modules with annotated savings rate tables, portfolio size calculations, and case studies of households pursuing different FIRE variants. Reflection prompts ask you to sketch your own FI number and the savings rate required to reach it on different timelines. This course is designed for working adults who are curious about financial independence and early retirement and want a clear, honest understanding of what it involves before making major life decisions. No prior financial knowledge beyond basic familiarity with investing is required. This course is educational and does not substitute for advice from a licensed financial advisor.