What is a FIRE number? (US guide)
Your FIRE number is the amount of invested capital you need to cover your annual spending without a paycheck. It is the simplest possible answer to the question: how much is enough? The most common shortcut is to divide your yearly outgoings by a safe withdrawal rate. A household spending $50,000 a year with a 4% withdrawal rate needs $1,250,000 invested. The same spending at 3.5% needs roughly $1,430,000.
TL;DR
- FIRE stands for Financial Independence, Retire Early.
- Your US FIRE number = annual spending divided by a withdrawal rate, usually 3.5% to 4%.
- Coast FIRE is the smaller amount you need today if you stop contributing and let growth do the rest.
- US tax wrappers such as 401(k)s, Roth IRAs, and HSAs change the tax path, but the final number is still driven by spending.
- Social Security, Medicare, inflation, and whether you carry a mortgage are the biggest US-specific adjustments.
- This is educational, not financial advice.
How much do I need to retire early in the US?
The honest answer is: it depends on how much you spend. The US version of FIRE benefits from the deepest equity market history on the planet, but that same depth makes it easy to overestimate safety. The 4% rule was born in US data. It says that withdrawing 4% of the starting portfolio in year one, then increasing withdrawals by inflation, survived a 30-year retirement in most historical US periods.
If you retire in your 40s or 50s, the planning horizon is longer than 30 years. Many US planners then use 3.5%, 3.25%, or even a flexible guardrail approach. The idea is the same everywhere: the longer the money must last, the more cautious the starting withdrawal should be.
| Annual spending | 3% withdrawal | 3.5% withdrawal | 4% withdrawal |
|---|---|---|---|
| $40,000 | $1,333,000 | $1,143,000 | $1,000,000 |
| $60,000 | $2,000,000 | $1,714,000 | $1,500,000 |
| $80,000 | $2,667,000 | $2,286,000 | $2,000,000 |
| $100,000 | $3,333,000 | $2,857,000 | $2,500,000 |
The table shows the trade-off. A couple spending $60,000 a year who accept a 4% starting withdrawal needs $1,500,000. If they want the extra cushion of 3.5%, they need $1,714,000. The right number depends on your age, flexibility, and how much of your spending is non-negotiable.
How do you calculate your FIRE number?
The calculation is two steps. First, work out your annual spending after tax. Second, divide it by a withdrawal rate you trust.
FIRE number = annual spending / withdrawal rate
Annual spending should include everything you will still pay once you no longer work. Housing, utilities, food, transport, insurance, healthcare, subscriptions, travel, and a margin for surprises. It should also include the tax you will still owe on withdrawals from tax-deferred accounts. Roth money is already tax-free, traditional 401(k) and IRA money is taxed as ordinary income, and taxable brokerage accounts owe capital gains and dividend taxes.
The withdrawal rate is the percentage of the portfolio you take in year one, then adjust for inflation in later years. The famous 4% rule comes from the 1998 Trinity Study by Cooley, Hubbard, and Walz, building on earlier work by William Bengen. It used US stock and bond data from 1926 to 1995. Later updates have extended the dataset, but the core idea has not changed: the portfolio must outpace both withdrawals and inflation.
Our calculator runs a seeded simulation so you can see how spending, savings, and retirement age change the shape of the answer. It is not a forecast. It is a stress test of the assumptions.
What is a safe withdrawal rate in the US?
A safe withdrawal rate is the one that lets your portfolio survive your planned retirement. The US has the longest and most studied market history, so 4% is a reasonable starting point for a 30-year retirement. But "starting point" is not the same as "safe forever".
Research since the Trinity Study has added nuance. Early retirees face sequence-of-returns risk, which means the order of good and bad years matters more than the average return. Low starting valuations in the 1920s and 1960s led to worse outcomes. High starting valuations in the late 1990s and late 2010s worried researchers. The result is a spectrum: 4% for a traditional 30-year retirement, 3.5% or lower for early retirement, and flexible withdrawal rules for everyone else.
US investors also benefit from a deep municipal bond market and a wide range of low-cost index funds. The Vanguard Total Stock Market Index and similar funds are common building blocks. The right asset allocation is usually a mix of US and global equities, plus bonds or cash to reduce volatility. The exact split changes the safe withdrawal rate, but the difference is usually smaller than the difference between 3.5% and 4%.
What is Coast FIRE and how is it different?
Coast FIRE is the amount you need invested today so that, with no further contributions, the portfolio grows to your full FIRE number by your target retirement age. It answers a different question: am I already so far ahead that I can stop saving?
The formula is:
Coast FIRE = FIRE number / (1 + expected return) ^ (target age - current age)
If your FIRE number is $1,500,000, you are 30, and you want to retire at 55, a 6% real return means your Coast FIRE number is roughly $391,000. If you already have $391,000 invested, you could theoretically stop contributing and still hit the target, assuming the return comes through. Most people do not stop, but the number is useful because it shows how much time already matters.
Our calculator shows Coast FIRE alongside your main FIRE number. It is the best single number for knowing whether you are ahead of schedule.
How do US tax accounts change the number?
The FIRE number itself is a pre-tax number. It tells you how much capital you need. The accounts tell you how efficiently you can get there and how much you will keep.
| Account | What it does | Relevance to FIRE |
|---|---|---|
| 401(k) / 403(b) | Tax-deferred workplace retirement plan | Best for funding life after age 59.5; reduces taxable income now |
| Traditional IRA | Tax-deferred individual retirement account | Similar to 401(k), often used when a workplace plan is unavailable |
| Roth IRA | Tax-free growth and withdrawals after age 59.5 | Ideal bridge between early retirement and 59.5 |
| HSA | Triple tax-advantaged health account | Powerful for health expenses, but not a substitute for retirement savings |
| Taxable brokerage | No special tax wrapper, subject to capital gains and dividends | Flexible, useful for early retirement before penalty-free account access |
The order of withdrawals matters. A typical US FIRE plan spends from the taxable brokerage first, then Roth contributions, then tax-deferred accounts after 59.5. Some early retirees use a Roth conversion ladder to move traditional 401(k) money into Roth IRA money over five years. The IRS rules on early withdrawals, required minimum distributions, and Roth conversions are complex, so treat this as a conversation to have with a tax professional, not a DIY recipe.
What about inflation, housing, and Social Security?
The 4% rule already includes inflation adjustments. You withdraw 4% in year one, then increase the dollar amount each year by inflation. This is why the portfolio needs real returns, not just nominal ones. The Federal Reserve targets 2% inflation, but actual inflation can spike, as it did in 2021 and 2022. A flexible withdrawal plan handles spikes better than a rigid rule.
Housing complicates the picture. If your home is paid off, your annual spending is lower. If you still have a mortgage, you need to include it. Some people include home equity in their net worth but not in their FIRE number, because you cannot easily spend a house without selling it or taking a reverse mortgage. Our calculator focuses on invested, liquid capital for exactly this reason.
Social Security is another adjustment. It starts as early as age 62, with full retirement age between 66 and 67 for most workers today, and delayed credits up to age 70. The benefit is inflation-adjusted and guaranteed. If your FIRE age is earlier, you can model it as a reduction in spending from Social Security age onward. Our calculator does not currently model this directly, so treat the number it gives you as a conservative estimate if you expect Social Security income later.
How do I use the calculator?
Start with annual spending. Be honest. Use the last twelve months of bank and credit card statements, not a budget you wish were true. Then pick a withdrawal rate. The slider defaults to 4%, but you can move it to 3.5% or lower if you want more safety.
Add your current savings and your monthly contribution. The chart shows the percentile bands from a seeded simulation. The darkening right edge is the Wedge of Death, a visual reminder that your money does not need to last forever, only until you are no longer alive to spend it.
Try the scenario chips. Save a baseline, then save an aggressive version and a conservative version. Switching between them is instant. The URL encodes your state, so you can copy a link and reopen it later. Your inputs never leave your browser.
What are the limits of the FIRE number idea?
The FIRE number is a planning tool, not a guarantee. It assumes constant spending, a fixed withdrawal rate, and average market behaviour. Real life is messier. You might spend more in some years, less in others. You might have children, change state, or face a health event. You might simply decide you enjoy work more than you expected.
The simulation behind the calculator uses fixed return assumptions. It does not predict the future. It tells you how the plan would have behaved under those assumptions. Use it to stress-test your spending and savings, not to decide your life.
Frequently asked questions
- What does FIRE stand for?
- FIRE stands for Financial Independence, Retire Early. It is a movement and a planning framework focused on building enough invested capital that work becomes optional.
- Is the 4% rule still safe in the US?
- The 4% rule is a useful benchmark for a 30-year US retirement. For early retirement, many planners use 3.5% or lower. Market valuations, bond yields, and spending flexibility all change the answer.
- Should I include my 401(k) in my FIRE number?
- Yes, but only the part you can access when you need it. A 401(k) counts for retirement after 59.5, but not for a FIRE plan that starts earlier. Roth contributions and taxable brokerage accounts are usually the bridge assets.
- What is Coast FIRE?
- Coast FIRE is the amount you need invested today so that growth alone reaches your full FIRE number by your target retirement age, with no further contributions.
- Does the calculator store my data?
- No. Your inputs stay in your browser using localStorage. You can also share a URL that encodes your state. Nothing is sent to our servers.
Last updated: 2026-08-02. Reviewed by Glenn Rodgers. This guide is educational and is not financial advice. Please speak to a qualified adviser before making investment or retirement decisions.