Financial Independence, Retire Early (FIRE) requires a clear understanding of the target portfolio size needed to sustain living expenses throughout retirement. This target, often referred to as the FIRE number, must account for the erosion of purchasing power caused by inflation. A simple calculation involves estimating annual expenses in todays dollars and multiplying that figure by a factor derived from the anticipated withdrawal rate. For instance, if annual expenses are projected to be $40,000 and a 4% withdrawal rate is adopted, the initial calculation yields a FIRE number of $1,000,000. However, this basic figure does not inherently address the ongoing impact of rising prices on those fixed expenses.
Incorporating inflation into FIRE number projections is vital because it provides a more realistic assessment of long-term financial security. Over time, the cost of goods and services increases, reducing the real value of savings and investment returns. Ignoring this factor can lead to an underestimation of the necessary portfolio size and potentially necessitate a return to work later in life. Historically, inflation has fluctuated, but its persistent presence underscores the necessity of factoring it into long-term financial planning to avoid eroding the real value of retirement income. By accounting for inflationary pressures, individuals gain a more accurate understanding of the funds required to maintain their desired lifestyle throughout retirement.