FIRE Number Calculator
Estimate the investment portfolio needed to fund your annual spending at a chosen safe withdrawal rate, with the multiple of spending. Includes the 4% rule example.
Results · USD
FIRE portfolio needed
- Multiple of spending
- 25×
- Annual spend
- $40,000.00
- Assumed SWR
- 4%
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Educational estimates · not financial advice · free, no signup
How this was calculated
Portfolio needed = annual spend ÷ (SWR ÷ 100). Classic 4% rule → 25× annual spending. Educational — markets and withdrawal plans vary.
Want more detail? Full formula notes & FAQs ↓
Detailed guide
What it is, how to use it, how to read the numbers, common mistakes, a worked example, formulas, and FAQs.
What this calculator is
FIRE, financial independence retire early, is the idea that once your investments can safely fund your spending, work becomes optional. The core calculation is simple: take your annual spending and divide by a safe withdrawal rate. At 4%, you need 25 times your annual spending; at 3.5%, about 28.6 times. The withdrawal rate comes from historical studies of how much a portfolio could pay out each year without running out over long periods, commonly summarised as the 4% rule. It is a rule of thumb, not a guarantee, and it depends on the time horizon, asset mix, fees, taxes, inflation and market conditions. Use it as a planning target, not an entitlement.
When to use / who it helps
- You want a target portfolio size for financial independence.
- You are comparing the effect of lowering spending versus saving more.
- You want to test a more conservative withdrawal rate.
- You are learning the 4% rule.
- You are setting savings goals.
How to use
Steps
- Enter your expected annual spending in retirement.
- Enter a safe withdrawal rate; 4% is the classic figure, and lower rates are more conservative.
- Read the portfolio needed.
- Read the multiple of spending.
- Compare with your current savings and the savings rate you can sustain.
- Run lower and higher withdrawal rates for a range.
How to interpret results
- The portfolio needed is spending divided by the withdrawal rate.
- Each $1,000 of annual spending adds $25,000 to the target at 4%.
- A lower withdrawal rate gives a larger, safer target.
- Early retirees with 40 or more years of withdrawals often choose rates below 4%.
- Taxes, healthcare and variable spending are not modelled.
Common mistakes & gotchas
- Treating 4% as a guarantee.
- Using pre-retirement spending when costs will differ.
- Ignoring taxes and healthcare.
- Forgetting inflation, since spending rises over time.
- Assuming a fixed return without sequence-of-returns risk.
Worked example
Worked example — $40,000 of annual spending
- At a 4% withdrawal rate, the portfolio needed is 40,000 ÷ 0.04 = $1,000,000.
- The multiple of spending is 1,000,000 ÷ 40,000 = 25.
- At a 3.5% rate: 40,000 ÷ 0.035 ≈ $1,142,857, or about 28.6 times spending.
- Cutting spending by $5,000 to $35,000 lowers the 4% target to $875,000.
Result: $40,000 of spending at 4% needs about $1,000,000, or 25 times annual spending.
To load the form's own demo values, tap Try example above the Calculate button.
How to calculate / formula
Portfolio needed = annual spend ÷ (SWR ÷ 100). Classic 4% rule → 25× annual spending. Educational — markets and withdrawal plans vary.
Frequently asked questions
What is the 4% rule?
A rule of thumb that you can withdraw about 4% of your starting portfolio each year, adjusted for inflation, with a good chance of lasting 30 years in historical data.
Is 4% safe for early retirement?
Longer horizons often call for lower rates, such as 3% to 3.5%, but outcomes cannot be guaranteed.
What spending should I use?
Use realistic annual spending including taxes, housing, healthcare and discretionary items.
Does the FIRE number include Social Security or pensions?
No. Other income would reduce the portfolio you need.
What returns does it assume?
None directly. The withdrawal rate summarises assumptions about returns and inflation.
Is this financial advice?
No. It is a planning aid, and results depend on future markets.