FIRE Calculator
Find out when you can retire by calculating your FIRE number using the 4% rule.
What is the FIRE Number?
Your FIRE number is the amount of money you need invested to retire early and live off your portfolio indefinitely. It's calculated using the 4% rule: multiply your annual expenses by 25. If you spend $40,000 per year, your FIRE number is $1,000,000. At that point, you can withdraw 4% annually and your portfolio should last 30+ years based on historical market returns.
Types of FIRE
| Type | Multiplier | Lifestyle | Example ($40k/yr spend) |
|---|---|---|---|
| Lean FIRE | 18.75x | Very frugal, minimal spending | $750,000 |
| FIRE | 25x | Current lifestyle maintained | $1,000,000 |
| Fat FIRE | 37.5x | Comfortable, flexible spending | $1,500,000 |
| Barista FIRE | 12.5x | Part-time work supplements income | $500,000 |
The Two Levers of FIRE
Reaching financial independence comes down to just two numbers: your savings rate and your annual spending. They are linked — cutting spending both lowers the pot you need (25× spending) and raises the amount you can save. Someone saving 15% of their income might take 40+ years to retire, while someone saving 50% can get there in around 17, and a 65% savings rate in roughly a decade. That is why the FIRE community obsesses over the savings rate far more than investment returns.
Flavours of FIRE
- Lean FIRE — a smaller pot (often under $1M) funding a deliberately frugal lifestyle.
- Fat FIRE — a larger pot for a comfortable, no-compromise retirement.
- Coast FIRE — investing enough early that growth alone reaches your number by traditional retirement age, so you only need to cover current expenses.
- Barista FIRE — semi-retiring with part-time work that covers some costs and often provides health cover, letting your investments keep growing.
Frequently Asked Questions
What is the 4% rule?
The 4% rule (also called the Safe Withdrawal Rate) states that you can withdraw 4% of your portfolio in year one of retirement, then adjust for inflation each year. Based on historical data, this strategy has a high probability of lasting 30+ years without running out of money.
What savings rate do I need to retire early?
Your savings rate is the key driver of FIRE. A 50% savings rate means you can retire in about 17 years. A 75% savings rate cuts that to just 7 years. Even going from a 10% to a 20% savings rate can shave 10+ years off your working life.
Does the FIRE calculator account for inflation?
The 4% rule already incorporates a historical inflation adjustment. However, if you want to be more conservative in the current environment, you can increase your target multiple to 30x (3.3% withdrawal rate) or 33x (3% withdrawal rate).
Can I achieve FIRE in the UK?
Yes — FIRE is very achievable in the UK. Key tools include ISAs (£20,000/year tax-free), SIPPs (pension with tax relief), and low-cost index funds. The UK State Pension (£11,973/yr from 2026) also reduces how much you need to save.
📖 Read the guide
What is a FIRE number?
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⚠️ Disclaimer: Results are estimates only and do not constitute financial, tax, or legal advice. Tax laws change frequently — always verify with official sources (IRS, HMRC) and consult a qualified professional before making decisions.
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