FIRE stands for Financial Independence, Retire Early — a movement built on the idea that aggressive saving and low-cost index investing can compress a 40-year working career into 15–25 years. Once your portfolio is large enough that the 4% safe withdrawal rate funds your annual spending, paid work becomes optional.

Your FIRE number is 25× your annual expenses — the portfolio target derived from the 4% rule and the 1998 Trinity Study. Spend $40,000 a year and you need $1,000,000 invested. Spend $80,000 and you need $2,000,000. The multiple stays the same; only your lifestyle determines the dollar value.

The 2026 version of FIRE has matured beyond the extreme-frugality stereotype. Sustained inflation from 2022 to 2024, longer life expectancies, and a deeper understanding of sequence of returns risk have pushed most planners toward more conservative withdrawal rates (3.3–3.5% for 40+ year retirements) and a stronger preference for flexibility over rigid targets. Read the full background in What is FIRE?

Every number on the chart comes from three formulas applied year by year. There is no machine learning, no proprietary model, no Monte Carlo simulation hidden behind the UI. The math is the math, and it is below in full.

Three details matter and they are easy to get wrong:

• Real, not nominal.Every projection is shown in today's purchasing power. A 7% nominal return with 3% inflation is roughly 3.9% real — the engine that actually compounds. See Inflation and Your FIRE Plan for the full Fisher-equation walkthrough.
• Inflated spending target. Your $50,000 lifestyle in 2026 becomes a $67,000 lifestyle in 2036 at 3% inflation. The calculator inflates the target each year so the FIRE date is honest, not flattering.
• Asset-weighted returns. Stocks have historically returned ~7% nominal long-term; bonds ~3–4%. The tool lets you set custom return assumptions for each bucket and weights them by your stocks/bonds split, rather than pretending one number fits every portfolio.

The Trinity Study (1998) and Bill Bengen's 1994 paper supply the empirical backbone — both tested withdrawal rates against actual US market history back to 1926. They are the source of the 4% rule itself, not arbitrary defaults.

1. 1

   Enter your current age and current savings.

   Total invested across retirement and taxable accounts — not cash sitting in checking.

2. 2

   Enter your monthly contribution.

   How much new money you add each month while still working. Be honest; rounding up is the most common self-sabotage.

3. 3

   Set your expected annual retirement spending.

   In today's dollars. The calculator inflates it forward each year so the target stays meaningful.

4. 4

   Choose a withdrawal rate (default 4%).

   Lower rates produce safer 40–50-year retirements. 3.3–3.5% is a common 2026 default for FIRE in your 30s or 40s.

5. 5

   Set asset allocation and expected nominal returns.

   Stocks vs bonds, with separate return assumptions. The blend produces a single weighted nominal return under the hood.

6. 6

   Add an inflation assumption.

   2.5% is the long-run US average; 3% is the 2026 default for most planners; 4% is a stress test worth running.

7. 7

   Read your FIRE number, FI age, and trajectory chart.

   The chart shows your real-dollar portfolio year by year against the inflated target. Hover for exact values.

Abstract formulas are easy to misread. These three scenarios use real inputs and the same engine you can run yourself in the calculator above. All figures assume a 7% nominal return, 3% inflation (≈3.9% real), and a 4% withdrawal rate.

Two patterns repeat in every realistic scenario. First, the gap between salaries matters less than the gap between savings rates — the high earner and the mid-career switcher reach FIRE in similar windows because they save similar shares of income. Second, the early starter wins on time, not on income. A 22-year runway with modest contributions beats a 12-year sprint at high contributions almost every time. The full mechanics are covered in the savings rate article.

FIRE is a spectrum, not a single number. Four variants dominate the 2026 conversation, and they differ on two axes: how much you spend in retirement, and whether you keep working in any form.

The variants are not mutually exclusive — most plans move through them. A common progression is Coast FIRE in the mid-30s, Barista FIRE in the early 40s, full Lean or Regular FIRE by the late 40s. Side-by-side detail lives in Lean FIRE vs Fat FIRE and Coast FIRE Explained.

1. Underestimating spending. The number on your budget is rarely the number you actually spend. Pull two years of actual transactions before committing to a target — most people are 10–20% over their stated budget.
2. Using 7% real return. 7% is a defensible nominal assumption for global equities; the real number after inflation is closer to 4–5%. Plans built on 7% real are off by years.
3. Ignoring sequence of returns risk. A 30% drawdown two years into retirement does far more damage than the same drawdown ten years in. Read the full mechanics in Sequence of Returns Risk.
4. Treating 4% as a guarantee. The 4% rule has a high historical success rate over 30 years. Over 50 years it weakens. For early retirees, 3.3–3.5% with a flexible-spending overlay is more honest. Background in the safe withdrawal rate article.
5. Optimizing for the spreadsheet instead of the life. Plans that compress the timeline by cutting everything that makes life worth living tend to break — usually around year 7. Sustainable plans build in slack.