Question 1

What is the FIRE number?

Accepted Answer

Your FIRE (Financial Independence, Retire Early) number is the total amount of money you need invested so you can live off your investment returns without ever running out of money. This is the magic number that tells you exactly when you can quit your job and retire for good.

How is it calculated?

The formula is simple:

FIRE Number = Annual Expenses ÷ Safe Withdrawal Rate

The most commonly used safe withdrawal rate is 4%, which comes from the Trinity Study. This means you multiply your annual expenses by 25 (since 1 ÷ 0.04 = 25). This is known as the Rule of 25.

Example: If you expect to spend $50,000 per year in retirement, and you use a 4% withdrawal rate:

FIRE Number = $50,000 ÷ 0.04 = $1,250,000

This means you need $1,250,000 invested. In your first year of retirement, you would withdraw $50,000 (4% of $1,250,000). Each year after, you adjust that amount for inflation. Historically, this approach has a 95% success rate over 30-year periods.

If you plan a longer retirement (40-50+ years), consider a more conservative 3-3.5% withdrawal rate. For $50,000/year at 3.5%, your FIRE number becomes $50,000 ÷ 0.035 ≈ $1,428,571.

Question 2

What is the 4% rule?

Accepted Answer

The 4% rule comes from the Trinity Study (1998), which analyzed US stock market data from 1926–1995. It found that withdrawing 4% of your portfolio in year one, then adjusting for inflation each year, had a 95% success rate over 30-year periods. For early retirees (40-50+ year retirements), many experts recommend a more conservative 3.0-3.5% withdrawal rate.

Question 3

What is Lean FIRE vs Fat FIRE?

Accepted Answer

Lean FIRE means retiring with minimal expenses ($25-40K/year), focusing on frugality and freedom. Regular FIRE targets a comfortable middle-class lifestyle ($40-80K/year). Fat FIRE means retiring with a luxury lifestyle ($100K+/year). Our calculator shows all three benchmarks to help you visualize your range.

How to read the Lean / Regular / Fat FIRE bar:

Below the results, you'll see a gradient bar that goes from green (Lean FIRE → $30K/year expenses) through yellow (Regular FIRE → $60K/year) to red (Fat FIRE → $120K/year). The exact dollar amounts for each tier are displayed below the bar, calculated using your chosen withdrawal rate.

A white vertical marker on the bar shows where your personal FIRE number falls. This helps you instantly see which lifestyle tier you're on track for — whether you're heading toward a lean, comfortable, or luxury retirement.

Question 4

How accurate is this calculator?

Accepted Answer

This calculator uses standard financial formulas (compound interest and the 4% rule) for educational purposes. It assumes constant returns, which rarely happens in reality — markets fluctuate. It also doesn't account for taxes, healthcare costs, or Social Security. Use it as a starting point, not financial advice.

Question 5

What is Coast FIRE?

Accepted Answer

Coast FIRE means you've saved enough that your investments will grow to your FIRE number by traditional retirement age without any additional contributions. You can 'coast' — work to cover only your living expenses while your nest egg compounds on its own.

Question 6

How can I reach FIRE faster?

Accepted Answer

The single biggest lever is your savings rate. Increasing it from 25% to 50% cuts your time to FIRE from ~32 years to ~17 years. Other strategies: earn more (side hustles, career growth), spend less (geo-arbitrage, minimalism), and invest wisely (low-cost index funds, tax-advantaged accounts).

Question 7

What is the Withdrawal Rate?

Accepted Answer

The withdrawal rate is the percentage of your portfolio you withdraw each year in retirement. It's the most critical assumption in FIRE planning because it directly determines how much you need to save.

How it works:

FIRE Number = Annual Expenses ÷ Withdrawal Rate

For example, if your annual expenses are $50,000:

• 4% withdrawal rate → $50,000 ÷ 0.04 = $1,250,000 (multiply expenses by 25)
• 3.5% withdrawal rate → $50,000 ÷ 0.035 ≈ $1,428,571 (multiply expenses by ~28.6)
• 3% withdrawal rate → $50,000 ÷ 0.03 ≈ $1,666,667 (multiply expenses by ~33.3)

As you can see, a lower withdrawal rate means a higher FIRE number because you need a larger portfolio to safely generate the same annual income.

Which rate should you choose?

• 4% (Standard) — Based on the Trinity Study. 95% success rate for 30-year retirements. Best for traditional retirees or those comfortable with some risk.
• 3.5% (Conservative) — Recommended for early retirees planning 40+ year retirements. Accounts for longer time horizons and market uncertainty.
• 3% (Ultra-Safe) — Maximum safety for 50+ year retirements. Provides significant buffer against market downturns, sequence of returns risk, and unexpected expenses.

The key trade-off: a lower withdrawal rate gives you more safety but requires more savings, meaning you'll need to work longer. Each 0.5% reduction adds roughly 2-4 years to your working career, depending on your savings rate. You can toggle between the three preset rates in the calculator to see how your FIRE number changes.

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