FIRE Number Calculator
Find out exactly how much you need to retire early — with bridge years, healthcare costs, and Social Security built in. Goes beyond the simple 25x rule.
Now check if your bridge years are funded
Your FIRE number shows the total target. The Bridge Strategy Calculator shows whether your taxable, 401(k), and Roth accounts are structured to actually get you there — year by year from retirement to age 90.
Model Your Bridge Plan →What Is a FIRE Number?
A FIRE number is the total portfolio size needed to sustain your lifestyle without working — the point at which your investments generate enough returns to cover your spending indefinitely. FIRE stands for Financial Independence, Retire Early, and the number is the central target of the movement.
The most common starting point is the 25x rule: multiply your annual spending by 25 to get your FIRE number. This is derived from the 4% rule — the idea that withdrawing 4% of a diversified portfolio annually has historically lasted 30 years in most market conditions.
However, for early retirement at 50, 52, or 55, the simple 25x rule significantly underestimates what you actually need. The calculator above accounts for the real complexity of early retirement: a longer retirement horizon, bridge years before retirement account access, healthcare before Medicare, Social Security timing, and a sequence of returns buffer.
Why the 4% Rule Underestimates for Early Retirement
The 4% rule was designed by financial planner William Bengen in 1994 for a 30-year retirement starting around age 65. It was never intended for 35-40 year retirements starting at 50-55. Research supports lower withdrawal rates for longer horizons:
At a 35-year horizon, a 3.7% withdrawal rate is more appropriate. At 40 years, 3.3%. At 45-50 years, 3.0-3.3%. These lower rates require significantly larger portfolios — a $60,000/year spender needs $1.5M at 4%, but $1.82M at 3.3%. That $320,000 difference is the cost of retiring 10-15 years early that the simple rule misses.
The calculator above uses research-adjusted withdrawal rates based on your target retirement age, automatically applying the correct rate for your retirement horizon.
The Four Components of a Real Early Retirement FIRE Number
1. Bridge account (taxable/Roth): The money needed to fund spending from retirement until age 59½, when retirement accounts become fully accessible. A 50-year-old needs 9.5 years of bridge funding; a 55-year-old needs 4.5 years. This bucket lives in taxable brokerage accounts and Roth contributions.
2. Retirement account balance (401k/IRA): The amount needed in tax-deferred accounts to fund spending after 59½, reduced by Social Security income. This is calculated using the adjusted withdrawal rate for your retirement horizon.
3. Healthcare buffer: The cost of health insurance before Medicare at age 65. A 50-year-old needs 15 years of coverage; a 55-year-old needs 10 years. Even with ACA subsidies, this is a significant cost that the simple 25x rule ignores entirely.
4. Sequence of returns buffer: An additional 1-2 years of spending as a cushion against a market crash in the first few years of retirement. Without this buffer, a bad early sequence can permanently impair the portfolio. See the Sequence of Returns Simulator to understand why this matters.
Frequently Asked Questions
What is the FIRE number for someone spending $50,000 per year?
At the simple 4% rule: $1,250,000. For early retirement at 50 (40-year horizon) with a 3.3% rate: $1,515,000 for the retirement account portion alone, plus bridge funding of roughly $220,000 (4.5 years at $50K), plus healthcare. Total real number for a 50-year-old spending $50K is typically $1.8M-$2.2M depending on healthcare and Social Security assumptions.
What is the difference between FIRE, lean FIRE, and fat FIRE?
FIRE (Financial Independence, Retire Early) is the general concept of building enough wealth to live without working. Lean FIRE targets a minimal budget, typically under $40,000/year. Fat FIRE targets a comfortable or affluent lifestyle, typically $80,000-$120,000+ per year. Coast FIRE means you have enough saved that it will grow to your FIRE number by traditional retirement age without additional contributions.
Does Social Security count toward my FIRE number?
Social Security reduces how much your portfolio needs to generate after it begins. A $24,000/year SS benefit at 67 reduces your required annual portfolio withdrawal by that amount. The calculator accounts for this by calculating the 401k/IRA portion based on spending minus SS income — reducing the total portfolio needed.
How does the bridge account fit into my FIRE number?
The bridge account is the taxable brokerage and Roth contribution portion of your portfolio that funds spending before age 59½. It is separate from your retirement account because it serves a different purpose — providing liquidity without penalty during the bridge years. Your total FIRE number includes both the bridge account and the retirement account balance.
Should I include my home equity in my FIRE number?
Generally no — home equity is illiquid and your primary residence doesn't generate income. Include only investable assets: taxable brokerage, IRAs, 401(k)s, and Roth accounts. A paid-off home can reduce your spending needs (no rent or mortgage), which indirectly lowers your FIRE number by reducing the annual spending figure.
What is the Coast FIRE number?
Coast FIRE is the amount you need saved today so that it will grow to your full FIRE number by traditional retirement age (65) without any additional contributions, assuming a historical market return of around 7% real. If you have reached your Coast FIRE number, you only need to earn enough to cover current expenses — your investments do the rest.