What is a FIRE number?
Your is the invested portfolio at which work becomes optional: enough index funds to fund your actual spending indefinitely. You don't need to want early retirement to use it. It is the price of not needing a job.
The formula, explained honestly
The calculation is one division:
FIRE number = annual spending ÷ safe withdrawal rate
- Annual spending. What you actually spend, not what you earn. Set a tax rate and the calculator grosses spending up, because a $42,000 lifestyle funded from a traditional 401(k) needs more than $42,000 of withdrawals.
- Safe withdrawal rate (SWR). The share of your portfolio you can withdraw each year, inflation-adjusted, with very high odds of lasting 30+ years. The classic figure is 4%, from the Trinity Study; conservative early retirees use 3.25–3.5%.
Spend $3,500 a month ($42,000 a year) at 4%? $42,000 ÷ 0.04 = $1,050,000. The projection uses real returns, converted as (1 + nominal) ÷ (1 + inflation) − 1, not naive subtraction.
A worked example
Devon spends $3,500 a month, has $60,000 invested, saves $2,000 a month, and assumes 7% nominal returns with 3% inflation, a real return near 3.9%.
- FIRE number: $42,000 ÷ 4% = $1,050,000 in today's dollars.
- At $2,000/month and ~3.9% real growth, the projection crosses $1.05M around age 56, about 24 years of saving from 32.
- Every $100/month of extra savings pulls the finish roughly a year closer. Every $100/month cut from spending does double duty: faster savings and a FIRE number lower by $30,000.
Reading your verdict
The panel gives one of three answers:
- Reached: withdrawals at your SWR cover your spending, and further work is a choice.
- On track: your contributions arrive on time. The subline names the crossing age.
- Behind: the panel prices the fix: an extra monthly contribution or a later date.
Flip the crash test to replay everything with your portfolio down 30%.
Common mistakes this calculator avoids
- Counting home equity you plan to keep living in.
- Using salary instead of spending.
- Assuming nominal returns and ignoring inflation.
- Forgetting taxes on traditional retirement accounts.
- Inflating the target with every raise.
Frequently asked questions
What exactly is a FIRE number?
It's the invested portfolio size that lets you live off withdrawals indefinitely. The standard estimate is annual spending divided by your safe withdrawal rate: spend $42,000 a year at 4% and your FIRE number is $1,050,000.
Is the 4% rule the right withdrawal rate for me?
The 4% figure comes from historical simulations of US stock-and-bond portfolios retiring into every market since 1926. It's a starting point, not a law. Early retirees often plan on 3–3.5%; a pension or Social Security covering part of your spending can justify higher effective rates. The advanced settings let you test both directions.
Why is my FIRE number different on other calculators?
Most calculators skip two adjustments this one makes. First, real returns: we convert nominal return minus inflation using (1 + nominal) ÷ (1 + inflation) − 1, which avoids the roughly 3–4% overstatement that naive subtraction introduces over 30 years at a 7% return and 3% inflation. Second, taxes: set a retirement tax rate and we gross up your spending so the target covers pre-tax withdrawals, not just take-home spending.
Should my FIRE number include my house or emergency fund?
No. The number counts only liquid, income-producing investments you'll draw from: index funds, ETFs, dividend stocks, bonds. Home equity you plan to live in, cash buffers and cars don't generate withdrawals, so including them hides the real gap.
What if I can't save enough to reach my number?
The verdict panel shows your two levers when you're behind: the extra monthly contribution that lands you at your target age, or how many years later your current pace gets you there — whichever feels cheaper. There's also a third lever the math can't compute: spending less changes the target itself. Dropping monthly spending by $500 cuts a typical FIRE number by $150,000.
How to calculate your FIRE number
Divide annual spending by your safe withdrawal rate. At 4% that is the same as multiplying by 25: spend $40,000 a year and 25 × $40,000 = $1,000,000. Two adjustments move the result in opposite directions:
- Retirement taxes raise it. At a 20% retirement tax rate, a $42,000 lifestyle needs $52,500 of gross withdrawals, so the target climbs from $1.05M to about $1.31M.
- Pensions lower it. Enter Social Security or a pension with its start age and the plan splits into a bridge fund before benefits and a smaller requirement after. An $18,000 annual benefit starting at 65 can cut the requirement by more than a quarter for someone retiring at 55.
Choosing a withdrawal rate, with a by-hand example
Three questions decide the rate. How many years must the money last? Retiring at 60 is a different problem from retiring at 35. How flexible is your spending? A rigid budget needs a more conservative rate than one you could trim 10% in a bad stretch. What arrives later? Pensions starting at a known age justify a higher effective rate.
By hand: take last year's real spending, including irregular costs. Say it was $52,000. At 4%, $52,000 ÷ 0.04 = $1,300,000; at 3.5%, ÷ 0.035 ≈ $1,486,000. That spread is the price of extra caution.
FIRE numbers at common spending levels
At a 4% withdrawal rate, your FIRE number is 25 times annual spending. These rows are before any tax adjustment:
| Monthly spend | Annual | FIRE number at 4% |
|---|---|---|
| $2,000 | $24,000 | $600,000 |
| $3,000 | $36,000 | $900,000 |
| $4,000 | $48,000 | $1,200,000 |
| $5,000 | $60,000 | $1,500,000 |
| $6,000 | $72,000 | $1,800,000 |
| $8,000 | $96,000 | $2,400,000 |
Roth-funded lifestyles can use these rows as-is. Traditional accounts need the tax-rate field above. Every dollar of recurring spending commits you to roughly 25 dollars of portfolio at 4%: a $600-a-year subscription is a $15,000 mortgage on your future self. A permanent $500/month cut lowers your target by $150,000 and raises your savings rate.
Geography and the limits of this table
Geography moves you between rows more than ambition does. The same person spending $4,000 a month in a high-cost city may spend $2,200 after relocating, dropping the implied target from $1.2M to $660,000 at 4%.
Every multiple inherits the assumptions of the withdrawal-rate research underneath it: a diversified portfolio, withdrawals rising with inflation, and historical US markets. It says nothing about sequence risk timing or taxes beyond the gross-up. Use the table to pick a direction and the projection chart above for the rest.
What is my FIRE number?
It is whatever your own spending and withdrawal rate produce. Spending $3,000 a month ($36,000 a year) gives $900,000 at 4%; $5,000 a month ($60,000) gives $1,500,000. Income sets how fast you get there; only spending sets where “there” is.
The rate matters too. The same $60,000-a-year life is a $1.5M problem at 4%, about $1.71M at 3.5% and $1.2M at 5%. Count everything, including health insurance and the annual trip, and revisit the number after marriage, kids, a move or a slower pace.
If your number feels impossibly far away
Progress toward a FIRE number is convex. The first $100,000 is usually the hardest, because early savings do the work while later savings mostly ride compounding. The second $100,000 typically arrives years faster.
Keep going
Know your number but want a checkpoint sooner? Try the Coast FIRE calculator or the savings rate calculator, or head back to the FireVerdict hub.