cost-calculation
FIRE Number Calculator (2026) — Financial Independence Retire Early
Financial Independence Retire Early (FIRE) is built on one number: the nest egg large enough that investment returns cover all your living expenses indefinitely. This calculator computes your FIRE number using the 4% safe withdrawal rate (25× annual expenses), tracks your progress, and shows how many years remain at your current savings rate — with Lean FIRE, Standard FIRE, Fat FIRE, and Coast FIRE variants.
Educational estimate based on the inputs you entered — not financial, legal, or tax advice. Verify against your specific situation before acting on this output.
How it works
Methodology
Inputs
- Annual expenses in retirement
- Your projected annual spending. Adjusted by FIRE variant multiplier (Lean 0.7×, Standard 1×, Fat 1.5×).
- Safe withdrawal rate
- Annual withdrawal as % of portfolio. 4% = 25× expenses (Trinity Study benchmark).
- Current invested balance
- Total investable net worth today (all accounts).
- Monthly savings rate
- Amount saved/invested each month.
- Expected annual return
- Expected average annual investment return. Historical S&P 500 real return ~7% (FRED).
- FIRE variant
- Adjusts annual expense target: Lean (×0.7), Standard (×1.0), Fat (×1.5), Coast (×1.0 but zero contributions).
- Current age + target FIRE age
- Used to compute required monthly savings to hit FIRE number by a specific age.
Formula
FIRE number = adjusted annual expenses / SWR Progress % = current balance / FIRE number × 100 Years to FIRE: binary search for t in FV = PV × (1 + r/12)^(12t) + PMT × ((1+r/12)^(12t) − 1) / (r/12) = FIRE number Coast FIRE years: t = ln(FIRE number / PV) / (12 × ln(1 + r/12)) Required monthly savings for target FIRE age: PMT_required = (FIRE number − PV × growth_factor) / ((growth_factor − 1) / (r/12))
Assumptions
- Returns are assumed constant at the stated rate; actual market returns are volatile.
- Monthly savings are constant. Actual savings often grow over a career.
- Inflation is not separately modeled; using real return (~7%) implicitly accounts for it.
- Coast FIRE assumes no additional contributions after the current date.
- Healthcare, Social Security, and taxes in retirement are not modeled — add those adjustments manually.
Worked examples
Standard FIRE — $50K/year lifestyle
- Annual expenses
- $50,000
- SWR
- 4%
- Current balance
- $100,000
- Monthly savings
- $2,500
- Return rate
- 7%
- Variant
- Standard FIRE
FIRE number: $1,250,000. At $2,500/month and 7% return, ~23 years to FIRE from $100K starting balance. Progress: 8%.
Fat FIRE — $80K/year lifestyle
- Annual expenses
- $53,333
- SWR
- 4%
- Current balance
- $200,000
- Monthly savings
- $4,000
- Return rate
- 7%
- Variant
- Fat FIRE
Fat FIRE adjusts to $80K annual expenses — FIRE number $2,000,000. At $4,000/month from $200K, approximately 22 years to target.
Frequently asked
Questions readers ask
What is the FIRE number? +
Your FIRE number is the investment portfolio size at which you can retire — defined as the point where a safe withdrawal rate (typically 4%) produces enough annual income to cover all your living expenses. At 4% SWR, the formula is: FIRE number = annual expenses × 25. A household spending $50,000/year needs a $1.25 million portfolio. Spending more or using a lower SWR (for a longer safety margin) raises the target.
What is the difference between Lean, Standard, Fat, and Coast FIRE? +
Lean FIRE targets a frugal lifestyle — typically 20-40% below standard expenses, achieved through geographic arbitrage or extreme frugality. Standard FIRE replaces a middle-class income without major cutbacks. Fat FIRE funds a comfortable lifestyle with travel, healthcare buffer, and legacy goals — typically 50%+ above standard expenses. Coast FIRE is a strategy where you save aggressively early, then stop contributing and let compounding grow to your FIRE number by a future date — no ongoing contributions needed.
Is the 4% rule still valid in 2026? +
The 4% rule (Trinity Study) has held up historically for 30-year retirements in U.S. market data. However, many FIRE practitioners — especially those planning 40-50 year retirements — use a lower withdrawal rate (3%–3.5%) as a safety margin. Lower expected long-term returns or higher inflation could also challenge the 4% assumption. The rule is a starting benchmark, not a guarantee; build in a buffer and stay flexible.
How does the calculator estimate years to FIRE? +
The calculator uses the future-value formula — solving for the number of months until your invested balance + ongoing contributions (at the stated return rate) reach your FIRE number. It uses binary search for the transcendental equation. Coast FIRE uses a simpler compounding formula with no contributions. The result is an estimate — actual market returns will deviate from the average.
What return rate should I assume for FIRE planning? +
The historical U.S. large-cap stock market has returned approximately 10% nominally and ~7% in real (inflation-adjusted) terms on a long-run average, per FRED historical data. Using the real return (~7%) implicitly adjusts for inflation and is a common conservative planning assumption. Past returns are not a guarantee of future results — FIRE planning at aggressive return assumptions introduces meaningful downside risk.
This tool is for educational purposes only and is not financial, legal, or tax advice. Final terms and eligibility depend on lender underwriting; consult a tax professional before acting on tax-tool output. ClearValue Lending is a funding platform.