Foundations
Build a portfolio big enough that a paycheck becomes a choice. A complete guide to finding your number and the path to reach it.
The one-sentence version: accumulate roughly 25× your annual spending in invested assets, then withdraw ~4% a year — so work becomes optional, not required.
The core idea
FIRE is the deliberate pursuit of financial independence — the point where your investments generate enough to cover your living costs for the rest of your life. "Retire early" doesn't necessarily mean never working again; for many it means work becomes a choice rather than a requirement.
The movement is built on a simple, unglamorous truth: spend less than you earn, invest the difference aggressively and consistently, and let compounding do the heavy lifting over a long enough timeline.
Your number
The foundational math: if you withdraw 4% of a diversified portfolio in year one and adjust for inflation after that, history says it should last ~30 years. Flip it around and your target is:
FIRE number ≈ 25 × annual spending
A $40,000 lifestyle needs about $1,000,000. A $60,000 lifestyle needs about $1,500,000. The number is personal — it's driven by what you actually plan to spend, not by a benchmark.
In NestPath, this is your target nest egg. Set it to 25× your expected retirement spending and the projection shows the age you reach it.
Flavors of FIRE
FIRE isn't one size. These tiers reflect different lifestyles and timelines — pick the one that matches the life you actually want.
| Tier | Spending | Number | What it looks like |
|---|---|---|---|
| Lean FIRE | ~$40k/yr | ~$1.0M | Minimalist living. Frugal, often lower-cost-of-living areas. |
| Standard FIRE | ~$60k/yr | ~$1.5M | Comfortable middle-class lifestyle without extravagance. |
| Fat FIRE | ~$100k+/yr | ~$2.5M+ | Generous lifestyle; requires a high savings rate and high income. |
| Barista FIRE | Partial | ~$500k–$750k | Cover basics with investments, work part-time for extras and health insurance. |
The four pillars
Savings rate
The % of income you keep. It is the single lever that controls your timeline — 50% gets you there in ~17 years, 10% in ~51 years.
Investing the gap
Saved money must be invested in low-cost, diversified index funds. Cash under a mattress does not compound — and inflation eats it.
Your number
Roughly 25× your annual spending. At a 4% withdrawal rate, that portfolio should sustain you for a typical 30-year retirement.
Lifestyle discipline
Keeping spending flat as income rises is what makes the math work. Lifestyle inflation is the quiet killer of early retirement.
The savings-rate math
The single biggest lever is your savings rate — the share of income you keep and invest. The timeline is roughly:
| Savings rate | Years to FIRE |
|---|---|
| 10% | ~51 years |
| 25% | ~32 years |
| 40% | ~22 years |
| 50% | ~17 years |
| 65% | ~10 years |
Assumes 5% real returns after inflation and starting from zero.
The relationship is exponential — doubling your rate from 10% to 20% doesn't halve the timeline, it cuts it by roughly 15 years. This is why small, early increases matter enormously.
Your path
Watch outs
The 4% rule isn't a guarantee
4% works historically for a 30-year window, but a bad first decade of returns (sequence risk) can break it. Many FIRE retirees use 3.5% for safety, or a flexible withdrawal.
Ignoring healthcare
Retiring before 65 means no Medicare. Budget for ACA premiums (often $400–$800/mo) — or plan Barista FIRE for employer coverage.
Underestimating spending
A surprise year of home repairs, a new car, or medical costs can blow a Lean FIRE budget. Pad your number by 10–15%.
One more year syndrome
Hitting the number but never feeling "safe enough" keeps you working indefinitely. Define your finish line in advance and trust the math.
In NestPath
FIRE is just retirement planning with a tighter timeline and a clearer number. In NestPath, set your target nest egg to 25× your expected annual spending, raise your per-account contributions, and drag the retirement age in the simulator to see exactly when you cross your number.
The projection chart and income simulator show whether your current plan reaches FIRE — or by how many years you fall short, and the contribution bump that closes the gap.
Run your projectionCommon questions
How is my FIRE number different from my NestPath target?
They're the same idea. NestPath's "target nest egg" is your FIRE number. Set it to 25× your expected annual retirement spending, and the projection shows when you reach it.
What savings rate do I need to retire early?
Roughly: 10% → 51 years, 25% → 32 years, 50% → 17 years, 65% → 10 years. The relationship is exponential — small increases early shave years off the end.
Is the 4% rule still safe?
For a 30-year retirement it held up in most historical periods. For longer retirements (FIRE often means 40–50 years), 3.5% or 3.75% is more conservative. Consider a flexible withdrawal that drops in bad years.
What about taxes in early retirement?
Money in a Roth IRA can be withdrawn (contributions) after 5 years penalty-free. A taxable brokerage has favorable long-term capital gains rates. A 401k has a 72(t) SEPP option for early access. Plan your withdrawal order with this in mind.