FIRE Calculator

FIRE Calculator

Financial Independence, Retire Early (FIRE) is built on one core insight: if your investment portfolio is large enough, the returns it generates will cover your living expenses indefinitely — making earned income optional. This calculator quantifies that goal. Enter your current savings, annual expenses, annual contributions, and expected investment return to find your FIRE number, track how close you are, and see the projected year you reach financial independence. Whether you are targeting Lean FIRE at $800,000 or Fat FIRE at $3,000,000, the math is the same — only the inputs change.

How the FIRE Calculation Works

The FIRE framework combines two formulas. First, your target portfolio size:

FIRE Number = Annual Expenses x 25

This derives from the 4% safe withdrawal rate — a portfolio of 25x expenses allows you to withdraw 4% annually with a high historical probability of lasting 30+ years. Second, the time required to reach that number from your current savings through ongoing contributions:

FV = PV x (1 + r)^n + PMT x [(1 + r)^n - 1] / r

Where PV is your current portfolio value, PMT is annual savings contributions, r is the expected annual return, and n is years. The calculator solves for n iteratively — finding the year when FV first equals or exceeds your FIRE number.

Worked Examples

Example 1 — Standard timeline. Age 32, $45,000 in savings, $60,000 annual income, 30% savings rate ($18,000/year), $42,000 annual expenses, FIRE number = $1,050,000, 7% return. Running the formula, FV crosses $1,050,000 in approximately 23 years — FIRE at age 55. Raising the savings rate to 40% ($24,000/year, $36,000 expenses, FIRE number $900,000) cuts the timeline to roughly 18 years — FIRE at 50.

Example 2 — Aggressive saver. Age 28, $80,000 income, 55% savings rate ($44,000/year), $36,000 expenses, FIRE number = $900,000, starting from $20,000 in savings, 7% return. The portfolio reaches $900,000 in approximately 13 years — FIRE at age 41. This is the classic “extreme savings” path made popular by the Mr. Money Mustache community.

Example 3 — Fat FIRE with higher income. Age 35, $200,000 income, 50% savings rate ($100,000/year), $100,000 annual expenses, FIRE number = $2,500,000, starting from $150,000 in savings, 7% return. The portfolio reaches $2,500,000 in approximately 15 years — FIRE at 50, with enough assets to fund a $100,000/year lifestyle indefinitely.

FIRE Timeline by Savings Rate

Assumes 7% annual return, starting from $0 savings. Years are approximate.

When to Use This Calculator

• You are starting out and want to know what savings rate you need to retire by a specific age
• You received a raise or bonus and want to model how directing extra income toward investments shifts your FIRE date
• You are considering a geographic or lifestyle change that would reduce your annual expenses and want to see the impact on your FIRE number
• You want to identify your Coast FIRE date — the point where you can stop contributing and let existing savings grow to your FIRE number by traditional retirement age
• You are already in the accumulation phase and want to track whether you are on pace against your original timeline

Common Mistakes

1. Using today’s expenses without inflation adjustment. $60,000/year in spending today will likely cost $90,000—$100,000 in 20 years at 2—3% annual inflation. A FIRE number based on current expenses without an inflation buffer understates the true target. Use real (inflation-adjusted) returns by reducing your expected return by the inflation rate — so 7% nominal becomes roughly 4—4.5% real — and your FIRE number calculation will stay accurate in today’s dollars.

2. Ignoring sequence-of-returns risk. A 4% withdrawal rate survived 95% of 30-year historical periods, but early years matter most. Retiring into a severe market downturn in year 1 or 2 — when your portfolio is at its peak — and selling assets at depressed prices to cover expenses is the most dangerous scenario. A 1-2 year cash buffer or a flexible “guardrail” approach (reducing withdrawals 10—15% in down years) dramatically improves portfolio survival rates.

3. Leaving out healthcare. Employer-sponsored health insurance costs are largely invisible to employees but average $8,000—$12,000 per person per year in employer contributions. Early retirees who lose that coverage must purchase individual plans. ACA marketplace premiums for a 45-year-old non-smoker run $400—$800/month depending on location and plan tier — $4,800—$9,600/year that most FIRE calculators do not include unless you add it to your annual expenses.

4. Assuming a static withdrawal rate. The 4% rule assumes you withdraw the same inflation-adjusted dollar amount every year regardless of market conditions. In practice, a flexible withdrawal strategy — spending 3.5% in bad markets and up to 5% in strong ones — extends portfolio longevity significantly. Calculators that use a fixed 4% give a good starting point, but real FIRE planning requires some flexibility in year-to-year spending.

Current Context for 2026

Reaching FIRE in 2026 means retiring into an environment with several meaningful variables. Inflation averaged 2.8% in 2025, down from the 2021—2023 peaks but above the Fed’s 2% target, which means FIRE numbers calculated 5 years ago may already be 15—20% too low in nominal terms. Stock valuations (S&P 500 CAPE ratio near 32—34) are above historical averages, which some researchers associate with lower forward 10-year returns of 5—7% rather than the historical 10%. Using a conservative 6—7% real return assumption for long FIRE timelines is more defensible than assuming 10% gross. On the positive side, high-yield savings and short-duration bond yields of 4.5—5.0% mean cash and near-cash holdings are generating real returns for the first time in over a decade — a meaningful advantage for the cash buffer portion of an early retiree’s portfolio.

Tips

1. Savings rate is the single most powerful lever — the difference between a 20% and a 50% savings rate can cut your timeline by 20 years, regardless of income level
2. Model Coast FIRE as an intermediate milestone; once you hit it, even if you stop saving, your existing portfolio will reach your FIRE number by age 65 with no further contributions
3. Consider a “barbell” approach: maximize tax-advantaged accounts (401k, IRA, HSA) for the far end, and keep a taxable brokerage for accessible funds before age 59.5
4. Build a 1—2 year living expenses cash cushion before your FIRE date so you do not need to sell equities during the first bear market of retirement
5. Run your FIRE number at multiple withdrawal rates — 3.5%, 4.0%, and 4.5% — to understand how much margin of safety you have and how it affects the required portfolio size
6. Account for healthcare costs explicitly — add $6,000—$12,000 per adult per year to your retirement expenses until Medicare kicks in at 65

Related Calculations

• Compound Interest Calculator — model how your current savings grow at different return rates over time
• Retirement Calculator — plan traditional retirement with Social Security income and required minimum distributions
• Investment Returns Calculator — verify whether your portfolio’s actual CAGR matches the return assumption in your FIRE plan