How to use this FIRE number calculator
- Enter what you expect to spend in retirement, monthly or yearly, in today's dollars.
- Pick a withdrawal rate and the age you want to retire, which sets how long the money must last.
- Turn on Social Security, a pension or part-time work if you expect them, then compare rates in the table.
The answer updates as you type. Tap any rate in the table to switch to it, copy the share link, or download the table as a CSV.
How is a FIRE number calculated?
The FIRE number is the portfolio whose withdrawals cover your spending:
FIRE number = annual spending ÷ safe withdrawal rate
At a 4% withdrawal rate that is 25 times your spending, the target popularized by the FIRE movement[1]. The 4% figure comes from William Bengen's 1994 study, where a 4% inflation-adjusted withdrawal lasted at least 33 years in every historical period he tested[2].
When Social Security or a pension starts later, the calculator values each retirement year's spending, minus the income paid that year, at the real rate at which your withdrawal rate lasts your whole retirement: 3.33% for 4% over 50 years. The years before the income starts get the same safety margin as the withdrawal rate, and with flat spending the result is exactly spending ÷ withdrawal rate. Your expected market return plays no part in the FIRE number.
Worked example
Sam wants to retire at 45 and spend $40,000 a year until at least 95.
- FIRE number at 4%: $40,000 ÷ 4% = $1,000,000 (25x spending)
- With a $24,000 Social Security benefit from 67: $782,483. The portfolio pays all $40,000 for 22 years, then only $16,000 a year.
- At 3.5% instead of 4%: $1,142,857 without Social Security.
What is my FIRE number? A quick table by monthly spending
If you think in monthly budgets, multiply by 12 and divide by your withdrawal rate. At 4% every $1,000 a month of spending needs $300,000 invested; at 3.5% it needs $342,857. These are the numbers before any Social Security, pension or part-time income.
| Monthly spending | At 4% (25x) | At 3.5% (28.6x) | At 3.25% (30.8x) |
|---|---|---|---|
| $2,000 | $600,000 | $685,714 | $738,462 |
| $3,000 | $900,000 | $1,028,571 | $1,107,692 |
| $4,000 | $1,200,000 | $1,371,429 | $1,476,923 |
| $5,000 | $1,500,000 | $1,714,286 | $1,846,154 |
| $6,000 | $1,800,000 | $2,057,143 | $2,215,385 |
| $8,000 | $2,400,000 | $2,742,857 | $2,953,846 |
| $10,000 | $3,000,000 | $3,428,571 | $3,692,308 |
Our calculation: monthly spending × 12 ÷ withdrawal rate. Today's dollars.
FI number, financial independence number and FIRE number all mean the same thing. The table is a starting point; the calculator above gives your own number after income that starts later and checks it against history.
What withdrawal rate should I use for my FIRE number?
The right rate depends on how long your retirement lasts. The 1998 Trinity study found that 4% withdrawals survived 95% to 98% of 30-year periods, depending on the stock and bond mix[3]. Stretch the same rule to 60 years and the success rate of a 50/50 portfolio falls to about 65%[4]. For 50-60 year retirements, rates of 3.25% to 3.5% survived even the worst historical conditions[5].
Our own backtest shows the same pattern. For $40,000 of spending and 80% stocks, replaying actual returns:
| Rate | FIRE number | 30-year success | 50-year success |
|---|---|---|---|
| 3% | $1,333,333 | 100% | 100% |
| 3.25% | $1,230,769 | 100% | 100% |
| 3.50% | $1,142,857 | 100% | 96% |
| 3.75% | $1,066,667 | 100% | 90% |
| 4% | $1,000,000 | 94% | 80% |
| 4.50% | $888,889 | 86% | 63% |
| 5% | $800,000 | 77% | 47% |
Our calculation: share of retirements starting in each year since 1928 that never ran out, using actual US returns and inflation minus 0.1% fees.
If you plan to retire before 50, a 3.25% to 3.5% rate (a FIRE number of 29 to 31 times spending) is the conservative choice. If you are close to a traditional retirement age, 4% is reasonable.
History may be kinder than the future. If returns average only 3.8% after inflation, which is our default expectation, the 50-year success rate at 4% falls from 80% to 43% and at 3.5% to 53%. Switch the calculator's risk test to "Match my return" under Assumptions to see your plan that way.
How much do you need to retire early at 40, 45, 50, 55 or 60?
With no other income, the FIRE number at a given withdrawal rate is the same at any age: $60,000 a year needs $1,500,000 at 4%. What changes with age is how long the money must last and how many years pass before Social Security starts. Here is the number for $60,000 a year with a $24,000 benefit from 67, money lasting to 95:
| Retire at | FIRE number at 4% | Lasted (4%) | FIRE number at 3.5% | Lasted (3.5%) |
|---|---|---|---|---|
| 40 | $1,328,240 | 73% | $1,490,724 | 89% |
| 45 | $1,282,483 | 71% | $1,437,514 | 88% |
| 50 | $1,224,067 | 74% | $1,371,213 | 89% |
| 55 | $1,150,014 | 83% | $1,289,367 | 93% |
| 60 | $1,057,824 | 91% | $1,190,487 | 100% |
| 65 | $947,690 | 94% | $1,076,490 | 100% |
Our calculation. "Lasted" is the share of retirement start years since 1928 in which that portfolio paid the spending to 95, with 80% stocks and actual returns minus 0.1% fees.
Retiring at 40 takes $1,328,240 at 4%, because the portfolio pays the full $60,000 for 27 years before the benefit starts. At 60 the bridge is only 7 years and the number falls to $1,057,824. The success columns show why early retirees use a lower rate: at 4% the retire-at-40 plan lasted in only 73% of historical start years, while 3.5% raised that to 89% for $162,484 more. Our guides to retiring at 40 and retiring at 55 cover the account access and healthcare questions for those ages.
What assumptions does the calculator use?
- Today's dollars. Spending and the FIRE number are in today's money; withdrawals rise with inflation each year. Inflation defaults to 3%. US inflation averaged 3% a year from 1928 to 2025 (our calculation from Damodaran's CPI data[7]) and was 3.7% in the 12 months to September 2026[9].
- Return: 7% before inflation. The S&P 500 returned 10.0% a year from 1928 to 2025[7], while Vanguard's 10-year forecast for US stocks is 4.8% to 6.8%[8]. The return does not change your FIRE number. It only matters if you switch the risk tests to "Match my return", which shifts history to average it.
- Plan to age 95. Change it under Assumptions. A longer plan means a longer test and usually a lower safe rate.
Read the full methodology for timing conventions and the historical data.
How does Social Security change your FIRE number?
It lowers it, and by more the sooner the benefit starts after you retire. In Sam's example, a $24,000 benefit from 67 lowers the target from $1,000,000 to $782,483, a 22% cut. Retire at 67 on $64,445 a year with the average benefit of $26,040 starting right away, and the cut is 40%. Full retirement age is 67 for anyone born in 1960 or later, and claiming at 62 cuts the benefit by 30%[10]. Workers with 35 or more years of covered earnings lose little of their benefit by stopping work early, but a shorter career means a smaller benefit[10], so use your own estimate[11] and consider counting only part of it.
How do pensions and part-time income change your FIRE number?
Any income you can count on lowers the number, but when it arrives matters as much as how big it is. The calculator splits the portfolio into a bridge (spending until the last income stream starts) and the long-term part after that, both valued with the same planning rate. For someone retiring at 45 on $50,000 a year at 3.5%:
| Other income | FIRE number | Bridge | Long-term | Lasted |
|---|---|---|---|---|
| No other income | $1,428,571 | $0 | $1,428,571 | 96% |
| Pension of $15,000 from 60 | $1,189,255 | $630,850 | $558,405 | 88% |
| Part-time work, $20,000 a year from 45 to 55 | $1,249,842 | $268,095 | $981,747 | 98% |
| Social Security of $20,000 from 67 | $1,197,928 | $851,964 | $345,965 | 88% |
| All three | $779,882 | $606,900 | $172,982 | 76% |
Our calculation, money lasting to 95; amounts in today's dollars. "Lasted" replays every start year since 1928 with 80% stocks.
A $15,000 pension from 60 cuts the number by $239,316. Part-time work worth $20,000 a year cuts it by $178,730 and also raised the historical success rate to 98%, because it pays for the first decade, when a market crash does the most damage. Income that starts late does the opposite: it shrinks the long-term part, so most of what remains is the bridge, spent in the riskiest years. With all three, the number falls to $779,882, but that smaller portfolio lasted in only 76% of start years, so lean on a lower rate or a cash cushion if your plan looks like that. Treat a pension that isn't fully inflation-linked as smaller than its starting amount, because its real value falls every year. For part-time plans, the Barista FIRE calculator projects the years in between.
FIRE numbers for different households
The same method gives very different answers depending on income, horizon and withdrawal rate:
| Household | 25x spending | Adjusted FIRE number | Lasted |
|---|---|---|---|
| Single, lean budget | $875,000 | $792,421 | 82% |
| Couple, retiring at 50 | $2,000,000 | $1,713,927 | 87% |
| Public-sector worker | $1,500,000 | $531,259 | 80% |
| Barista FIRE at 40 | $1,125,000 | $788,482 | 95% |
| Fat FIRE couple at 40 | $3,750,000 | $4,202,143 | 95% |
Our calculation, money lasting to 95, 80% stocks, actual returns minus 0.1% fees.
- Single, lean budget: Retires at 45 on $35,000; $18,000 of Social Security from 67; 3.5%.
- Couple, retiring at 50: $80,000 a year; $40,000 of combined Social Security from 67; 3.5%.
- Public-sector worker: Retires at 55 on $60,000 with an inflation-linked $30,000 pension from 55 and $15,000 of Social Security from 67; 4%.
- Barista FIRE at 40: $45,000 a year; $25,000 from part-time work until 55; $20,000 of Social Security from 67; 3.5%.
- Fat FIRE couple at 40: $150,000 a year; $45,000 of Social Security from 70; 3.25%.
The public-sector worker needs the least because a pension starting on day one covers half the budget. The Fat FIRE couple needs more than 25x because a 3.25% rate suits a 55-year retirement, and their benefit doesn't start until 70. For couples, remember that a spouse with little work history can claim up to 50% of the other's benefit at full retirement age, and a widow or widower keeps the larger of the two benefits, not both[10]. Plan for spending that falls less than the income after one death.
What is a good FIRE number?
A good FIRE number is one built from your own spending, at a withdrawal rate that fits your retirement length. Official spending data gives a sense of scale. US households spent an average of $81,905 in 2025, and spending peaks in midlife and falls later[14]:
| Age of household head | Average spending, 2025 | FIRE number at 4% | At 3.5% |
|---|---|---|---|
| 35-44 | $93,650 | $2,341,250 | $2,675,714 |
| 45-54 | $106,658 | $2,666,450 | $3,047,371 |
| 55-64 | $85,442 | $2,136,050 | $2,441,200 |
| 65-74 | $69,333 | $1,733,325 | $1,980,943 |
| 75 and older | $57,959 | $1,448,975 | $1,655,971 |
Spending: BLS Consumer Expenditure Surveys, 2025. FIRE numbers: our calculation, before Social Security or pensions.
Those averages include costs that stop when you stop working. The $81,905 average contains $10,175 of "personal insurance and pensions"[14], a category that includes Social Security payroll taxes and contributions to retirement plans[16]. Take it out and the average household's FIRE number at 4% falls from $2,047,625 to $1,793,250. By income, the middle fifth of households spent $68,983 and the top fifth $159,512[15], FIRE numbers of $1,724,575 and $3,987,800 at 4%. If your budget is well below these averages, the Lean FIRE calculator fits your plan; if it is well above, try the Fat FIRE calculator.
Once you know your number, the FIRE calculator shows when you will reach it, and the Coast FIRE calculator shows when you could stop saving. Planning a traditional retirement instead? Try how much do I need to retire. For the full method, read how to calculate your FIRE number.