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Your FIRE number is your annual expenses divided by your safe withdrawal rate. If you spend $42,000 per year and use the 4% rule, you need $1,050,000 invested to retire. The FIRE calculator tells you exactly how many years that will take based on your current savings, income, expenses, and expected returns.
That is the entire FIRE movement in one sentence. Everything else — the subreddits, the blogs, the podcasts — is optimization around those variables. Earn more, spend less, invest the difference, and compound growth does the heavy lifting.
Enter five numbers:
The calculator outputs your FIRE number, years to FIRE, projected retirement year, savings rate, gap to FIRE, and whether you are on a Lean, Regular, Fat, or Ultra Fat FIRE path.
Calculate your FIRE number and retirement date right now.
Open FIRE Calculator →| Scenario | Income/mo | Expenses/mo | Savings Rate | FIRE Number | Current Savings | Years to FIRE |
|---|---|---|---|---|---|---|
| Entry-level FIRE | $4,000 | $2,500 | 37.5% | $750,000 | $15,000 | ~18 years |
| Aggressive saver | $6,000 | $2,500 | 58.3% | $750,000 | $50,000 | ~12 years |
| High earner | $10,000 | $4,000 | 60% | $1,200,000 | $200,000 | ~10 years |
| Lean FIRE | $5,000 | $1,800 | 64% | $540,000 | $30,000 | ~9 years |
| Fat FIRE | $15,000 | $8,000 | 46.7% | $2,400,000 | $500,000 | ~14 years |
| Already ahead | $7,000 | $3,500 | 50% | $1,050,000 | $400,000 | ~7 years |
All examples use 7% expected return and 4% SWR. Your numbers will differ — run your own scenario.
The FIRE number formula is intentionally simple:
FIRE Number = Annual Expenses ÷ Safe Withdrawal Rate
Notice something: your FIRE number is entirely about expenses, not income. A doctor earning $300,000 who spends $120,000 per year needs $3 million. A teacher earning $55,000 who spends $25,000 per year needs $625,000. The teacher might reach FIRE first if their savings rate is higher.
This is the most counterintuitive part of FIRE: reducing expenses works double. Cutting $500/month from expenses both adds $500/month to savings AND reduces your FIRE number by $150,000 (at 4% SWR). No raise gives you that kind of leverage.
| Savings Rate | Approximate Years to FIRE* | Who Is Typically Here |
|---|---|---|
| 10% | ~50+ years | Average American worker |
| 20% | ~37 years | Intentional saver |
| 30% | ~28 years | Serious about FIRE |
| 40% | ~22 years | Optimizing hard |
| 50% | ~17 years | The FIRE sweet spot |
| 60% | ~12.5 years | High earner or very frugal |
| 70% | ~8.5 years | Extreme optimization |
| 80% | ~5.5 years | Tech worker living on half salary |
| 90% | ~2.5 years | Already wealthy, just running the math |
*Assumes 7% real return, starting from $0 savings, 4% SWR. Starting with existing savings shortens these timelines.
The jump from 30% to 50% savings rate cuts roughly 11 years off your FIRE timeline. That is the most impactful range for most people — achievable through a combination of income growth and expense control without the extreme lifestyle compression that 70%+ requires.
| Type | Annual Expenses | FIRE Number (4% SWR) | Lifestyle |
|---|---|---|---|
| Lean FIRE | < $40,000 | < $1,000,000 | Frugal but comfortable. Shared housing or low-cost area. Cooking at home. Limited travel. |
| Regular FIRE | $40,000 - $60,000 | $1M - $1.5M | Moderate lifestyle. Own housing in a reasonable market. Some travel. Normal spending. |
| Fat FIRE | $80,000 - $120,000 | $2M - $3M | Comfortable with room. Nice area. Regular travel. No budget anxiety. |
| Ultra Fat FIRE | $150,000+ | $3.75M+ | Premium lifestyle. High-cost city. Frequent travel. Financial freedom with luxury. |
The calculator automatically classifies your FIRE type based on your annual expenses. There is no moral hierarchy — Lean FIRE is not "more disciplined" and Fat FIRE is not "more successful." They reflect different life choices, cost-of-living situations, and personal values.
Every dollar you cut from monthly expenses does two things: increases your monthly savings AND lowers your FIRE number. Cutting $300/month saves $3,600/year and reduces your FIRE number by $90,000. That single change can shave 2-3 years off your timeline.
Going from 30% to 50% savings rate is the single most impactful change for most people. It is also the hardest. If you earn $6,000/month, that means cutting $1,200/month from expenses — roughly the difference between a $1,500/month apartment and a $800/month shared rental, plus cooking instead of eating out.
The difference between 5% and 7% returns adds roughly 4-5 years to a 15-year FIRE timeline. But this variable is the one you have least control over. Markets do what markets do. Use 7% as a reasonable baseline, but run the numbers at 5% too to see how your timeline holds up in a pessimistic scenario.
Dropping from 4% to 3.5% SWR increases your FIRE number by 14.3%. On $50,000 annual expenses, that is the difference between needing $1,250,000 (at 4%) and $1,428,571 (at 3.5%). Worth it for the extra safety margin if your retirement will be 40+ years. Our retirement compound interest guide covers how these numbers interact with 401k and IRA contributions.
Run your own numbers — income, expenses, savings, returns.
Calculate Your FIRE Number →Reaching your FIRE number does not mean you must stop working immediately. Options include:
Use our compound interest calculator to model how your portfolio grows after you stop contributing — this shows you the Coast FIRE math in action. For overall budget planning during your FIRE journey, our budget calculator uses the 50/30/20 framework.