FIRE stands for Financial Independence, Retire Early. The core idea: save and invest aggressively (often 40–70% of income) so that portfolio income can cover lifestyle expenses indefinitely, allowing early or optional retirement years or decades before traditional retirement age.

What is a FIRE number?

Your FIRE number is the portfolio size needed to safely fund your annual expenses indefinitely. The standard calculation is annual expenses divided by the safe withdrawal rate. At 4% withdrawal, the FIRE number is 25× annual expenses — so $40,000 of annual spending requires $1 million invested.

The 4% rule, from the Trinity Study, suggests retirees can safely withdraw 4% of their starting portfolio in year 1 (then adjust the dollar amount upward for inflation each year) with high historical success rate over 30 years. For longer retirements (40+ years), many FIRE planners use 3.0–3.5% instead.

What are the FIRE variants?

Lean FIRE (very low expenses, ~$25K/year), Regular FIRE (~$40–60K/year), Fat FIRE (high expenses, $100K+/year), Coast FIRE (existing portfolio will grow to FIRE size by traditional age — stop aggressive saving), and Barista FIRE (partial income from low-stress work supplements portfolio draw). The math is the same; the lifestyle assumptions differ.

Is FIRE realistic for most people?

Strict early-30s FIRE requires income meaningfully above expenses — usually solid professional income combined with frugal lifestyle. More moderate variants (Coast FIRE, Barista FIRE, FIRE at 50 instead of 40) are achievable for many middle-class earners who start in their 20s or 30s. The math always favors starting early — savings rate matters more than income, but time matters most.

FIRE Calculator

Find out how long until you reach financial independence using the FIRE method. Enter your income, expenses, savings, and expected returns to calculate your FIRE number and the years until you can retire early. Based on the 4% safe withdrawal rate rule.

Last updated: May 25, 2026Reviewed by the CalcMountain editorial team

About this calculator

FIRE — Financial Independence, Retire Early — is a personal-finance movement built on a deceptively simple insight: you don't need to wait until 65 to stop working if you've saved enough that your portfolio can sustainably support your lifestyle. The "enough" number is your FIRE number, typically calculated as annual expenses divided by a safe withdrawal rate (usually 4%). At a $40,000-per-year lifestyle, FIRE is $1 million; at $80,000, it's $2 million.

The math has two main levers: savings rate (the percentage of income you save) and time. The math is brutal at low savings rates and remarkably fast at high ones. Save 10% of income, and you need roughly 50 years to reach FIRE. Save 50%, and you can reach FIRE in about 17 years. Save 70%, and it's about 8 years. The savings rate matters far more than the absolute income level — a $60K earner saving 50% will hit FIRE before a $200K earner saving 20%.

This calculator models the time to FIRE based on your income, expenses, current savings, expected return, and chosen safe withdrawal rate. The 4% rule (from the Trinity Study, examining historical 30-year retirements) is the standard starting point but is hotly debated. More conservative planners use 3.0–3.5% for very long retirements (40+ years), trading slower progress to FIRE for more safety in retirement. The output is the year you'd cross your FIRE number — treat it as a directional target, not a guarantee.

Formula

FIRE number (the target portfolio size): FIRE Number = Annual Retirement Expenses / Safe Withdrawal Rate Equivalently: FIRE Number = Annual Retirement Expenses × (1 / Withdrawal Rate) At 4% withdrawal: FIRE Number = 25 × Annual Expenses At 3.5%: 28.6 × Annual Expenses At 3.0%: 33.3 × Annual Expenses Annual savings: Savings = After-Tax Income − Annual Expenses Savings rate: Savings Rate = Savings / After-Tax Income Years to FIRE (single-formula approximation, ignoring inflation): If we know the savings rate s and expected real return r, years to FIRE from $0 is: T ≈ ln(1 + r × FIRE_factor / s) / ln(1 + r) Where FIRE_factor = 1/withdrawal_rate (e.g., 25 for 4% withdrawal). Year-by-year accurate version: For year t = 0, 1, 2, ...: Portfolio(t+1) = Portfolio(t) × (1 + r) + Annual Savings Stop when Portfolio(t) ≥ FIRE Number. Example: Income $80,000, expenses $45,000, savings $35,000, savings rate 43.75%, current portfolio $100,000, 7% real return, 4% withdrawal rate, retirement expenses $40,000. FIRE Number = $40,000 / 0.04 = $1,000,000 Year 0: $100,000 Year 5: $100,000 × 1.07^5 + 35,000 × [(1.07^5 − 1)/0.07] ≈ $342,000 Year 12: ≈ $828,000 Year 14: ≈ $1,032,000 → crosses FIRE Time to FIRE: ~14 years. Savings-rate-only approximation (assumes $0 starting and 5% real return): Savings rate 20%: ~37 years Savings rate 40%: ~22 years Savings rate 60%: ~13 years Savings rate 75%: ~7 years

How to use this calculator

Enter your annual after-tax income — what actually hits your bank account each year. Use take-home pay, not gross.
Enter your current annual expenses. Be honest — track real spending for a few months if you don't already. Most people underestimate by 15–25%.
Enter current savings and investments — anything that's actually invested for the long term (401(k), IRAs, taxable brokerage, HSA). Don't include your emergency fund or short-term cash.
Enter an expected annual real return. Use 5–7% for a diversified equity-heavy portfolio (real, meaning inflation-adjusted). Use 4–5% for a moderate allocation, 3% for conservative.
Set the safe withdrawal rate. 4% is the standard, calibrated against 30-year retirements. For early retirees with potentially 40–50 year retirements, more conservative planners use 3.0–3.5%.
Enter your expected annual expenses in retirement. Many FIRE planners assume the same as current expenses; others assume lower (relocate, downsize, no work-related costs) or higher (more travel, more healthcare).
Review three numbers: your FIRE number (the target), your current savings rate, and the projected years to FIRE. Increase savings rate by reducing expenses or growing income to accelerate.
Re-run with different withdrawal rates and return assumptions to understand sensitivity. A "4%" plan can become a "3.5%" plan in retirement if early returns are weak — building in conservatism upfront is cheaper than fixing it later.

Worked examples

Aggressive saver — 60% savings rate

After-tax income: $90,000. Expenses: $36,000. Savings: $54,000 (60% rate). Current portfolio: $50,000. Expected real return: 6%. 4% withdrawal. Retirement expenses: $36,000. FIRE Number: $36,000 / 0.04 = $900,000. Time to FIRE: approximately 13 years. The 60% savings rate is what makes early FIRE feasible in 10–15 years. It requires intentional lifestyle design: lower housing cost, no car payments, modest discretionary spending, strong career.

Standard saver — 20% savings rate

After-tax income: $80,000. Expenses: $64,000. Savings: $16,000 (20% rate). Current portfolio: $50,000. Expected real return: 6%. 4% withdrawal. Retirement expenses: $64,000. FIRE Number: $64,000 / 0.04 = $1,600,000. Time to FIRE: approximately 33 years. At 20% savings, FIRE is essentially traditional retirement timing. The savings rate dictates the timeline — there's no path to early retirement without an above-average savings rate.

Coast FIRE — partial early independence

Currently age 35. Already saved $400,000. Expenses $60,000. At 6% real return for 30 years (no further contributions): $400,000 × 1.06^30 ≈ $2,300,000. Coast FIRE: your existing portfolio will grow to FIRE size by traditional retirement age (65) without further contributions. You can stop saving aggressively, work less stressful jobs, or pursue passion work — as long as new income covers current expenses, the portfolio takes care of long-term retirement on its own. A popular variant of FIRE for people who want to step off the savings treadmill without fully retiring early.

When to use this calculator

Use this calculator at any career stage to understand the relationship between savings rate, expected returns, and time to financial independence. It's most powerful as a sensitivity tool: rerun it at 30%, 40%, and 50% savings rates to see how much each marginal percentage point of saving compresses the timeline. The answer is usually surprisingly large.

For early career (20s–30s), this is the most important calculator in personal finance. The compounding window is at its peak; small changes to savings rate have decades to play out. Increasing savings rate from 20% to 40% can cut time to FIRE by 15+ years.

For mid-career (40s), the calculator is useful for setting realistic expectations. If you didn't start aggressive saving in your 20s, FIRE in your 40s may not be feasible — but FIRE in your early-to-mid 50s often still is. The math is honest about what's possible from where you stand today.

Pair this with the retirement-savings calculator (the broader retirement projection), the compound-interest calculator (to see the underlying growth), the cost-of-living calculator (since reducing expenses through geographic arbitrage is a popular FIRE tactic), and the IRA / 401(k) calculators (since tax-advantaged accounts dominate most FIRE portfolios).

A serious caveat: the 4% rule was developed for 30-year retirements. If FIRE means a 50-year retirement, sequence-of-returns risk (a bad market in the early years can permanently impair the plan) is much higher. Many FIRE adherents use 3.0–3.5% withdrawal rates as a result, or build in a flexible withdrawal strategy (Guyton-Klinger guardrails, variable percentage withdrawal) to adapt to market conditions.

Common mistakes to avoid

Confusing "after-tax income" with gross. Use take-home pay (what actually hits your account after taxes, 401(k) contributions, healthcare premiums) for the math to work — gross income overstates what you can actually save.
Forgetting healthcare in early retirement. Medicare doesn't start until 65; if you retire at 45, you need 20 years of independent health coverage. ACA marketplace plans, COBRA bridges, and spouse-employer coverage are the typical routes, all materially expensive.
Using nominal returns instead of real returns. The 4% rule was calibrated against inflation-adjusted returns. A 10% nominal return at 3% inflation is roughly 7% real. Mixing nominal returns with the 4% rule overstates the safe withdrawal.
Assuming retirement expenses equal current expenses. Some categories drop (commuting, work clothes, pre-retirement contributions, work meals); others rise (healthcare, travel, leisure). Realistic FIRE planning models these separately, not as a flat percentage.
Ignoring sequence-of-returns risk. The Trinity Study's "very high success rate" includes scenarios where the portfolio comes uncomfortably close to depletion when early-retirement returns are weak. A flexible withdrawal strategy that reduces spending in down years is much safer than the rigid 4%-of-original-portfolio version.
Treating Social Security as zero. Even early retirees will eventually claim Social Security (62–70 depending on strategy). It's a meaningful inflation-adjusted income stream that reduces the portfolio draw needed in later decades, but only matters once claimed.

Frequently Asked Questions

Sources & further reading

Trinity Study — Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable — American Association of Individual Investors
Saving and Investing — beginner's guide — U.S. Securities and Exchange Commission
Social Security Quick Calculator — official benefit estimate — U.S. Social Security Administration

FIRE Calculator

Inputs

Annual After-Tax Income

Annual Expenses

Current Savings/Investments

Expected Annual Return

Safe Withdrawal Rate

4% is the standard rule of thumb

Annual Expenses in Retirement

Often lower than current expenses

Results

FIRE Number

$1,000,000

Years to FIRE

14 years

Savings Rate

43.8%

Annual Savings

$35,000

Year-by-Year Breakdown

Year	Annual Savings	Growth	Portfolio	% to FIRE
1	$35,000.00	$7,000.00	$142,000.00	14.20%
2	$35,000.00	$9,940.00	$186,940.00	18.69%
3	$35,000.00	$13,085.80	$235,025.80	23.50%
4	$35,000.00	$16,451.81	$286,477.61	28.65%
5	$35,000.00	$20,053.43	$341,531.04	34.15%
6	$35,000.00	$23,907.17	$400,438.21	40.04%
7	$35,000.00	$28,030.67	$463,468.89	46.35%
8	$35,000.00	$32,442.82	$530,911.71	53.09%
9	$35,000.00	$37,163.82	$603,075.53	60.31%
10	$35,000.00	$42,215.29	$680,290.81	68.03%
11	$35,000.00	$47,620.36	$762,911.17	76.29%
12	$35,000.00	$53,403.78	$851,314.95	85.13%

Last updated: May 25, 2026Reviewed by the CalcMountain editorial team

About this calculator

Formula

How to use this calculator

Enter your annual after-tax income — what actually hits your bank account each year. Use take-home pay, not gross.
Enter your current annual expenses. Be honest — track real spending for a few months if you don't already. Most people underestimate by 15–25%.
Enter current savings and investments — anything that's actually invested for the long term (401(k), IRAs, taxable brokerage, HSA). Don't include your emergency fund or short-term cash.
Enter an expected annual real return. Use 5–7% for a diversified equity-heavy portfolio (real, meaning inflation-adjusted). Use 4–5% for a moderate allocation, 3% for conservative.
Set the safe withdrawal rate. 4% is the standard, calibrated against 30-year retirements. For early retirees with potentially 40–50 year retirements, more conservative planners use 3.0–3.5%.
Enter your expected annual expenses in retirement. Many FIRE planners assume the same as current expenses; others assume lower (relocate, downsize, no work-related costs) or higher (more travel, more healthcare).
Review three numbers: your FIRE number (the target), your current savings rate, and the projected years to FIRE. Increase savings rate by reducing expenses or growing income to accelerate.
Re-run with different withdrawal rates and return assumptions to understand sensitivity. A "4%" plan can become a "3.5%" plan in retirement if early returns are weak — building in conservatism upfront is cheaper than fixing it later.

Worked examples

Aggressive saver — 60% savings rate

Standard saver — 20% savings rate

Coast FIRE — partial early independence

When to use this calculator

Common mistakes to avoid

Confusing "after-tax income" with gross. Use take-home pay (what actually hits your account after taxes, 401(k) contributions, healthcare premiums) for the math to work — gross income overstates what you can actually save.
Forgetting healthcare in early retirement. Medicare doesn't start until 65; if you retire at 45, you need 20 years of independent health coverage. ACA marketplace plans, COBRA bridges, and spouse-employer coverage are the typical routes, all materially expensive.
Using nominal returns instead of real returns. The 4% rule was calibrated against inflation-adjusted returns. A 10% nominal return at 3% inflation is roughly 7% real. Mixing nominal returns with the 4% rule overstates the safe withdrawal.
Assuming retirement expenses equal current expenses. Some categories drop (commuting, work clothes, pre-retirement contributions, work meals); others rise (healthcare, travel, leisure). Realistic FIRE planning models these separately, not as a flat percentage.
Ignoring sequence-of-returns risk. The Trinity Study's "very high success rate" includes scenarios where the portfolio comes uncomfortably close to depletion when early-retirement returns are weak. A flexible withdrawal strategy that reduces spending in down years is much safer than the rigid 4%-of-original-portfolio version.
Treating Social Security as zero. Even early retirees will eventually claim Social Security (62–70 depending on strategy). It's a meaningful inflation-adjusted income stream that reduces the portfolio draw needed in later decades, but only matters once claimed.

Frequently Asked Questions

Sources & further reading

Trinity Study — Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable — American Association of Individual Investors
Saving and Investing — beginner's guide — U.S. Securities and Exchange Commission
Social Security Quick Calculator — official benefit estimate — U.S. Social Security Administration

About this calculator

Formula

How to use this calculator

Worked examples

Aggressive saver — 60% savings rate

Standard saver — 20% savings rate

Coast FIRE — partial early independence

When to use this calculator

Common mistakes to avoid

Frequently Asked Questions

What is FIRE?

What is a FIRE number?

What is the 4% rule?

What are the FIRE variants?

Is FIRE realistic for most people?

Sources & further reading

Related Calculators

Retirement Savings Calculator

401(k) Calculator

Compound Interest Calculator

Pension Calculator

72(t) SEPP Calculator

457 Plan Calculator

Inputs

Results

Year-by-Year Breakdown

About this calculator

Formula

How to use this calculator

Worked examples

Aggressive saver — 60% savings rate

Standard saver — 20% savings rate

Coast FIRE — partial early independence

When to use this calculator

Common mistakes to avoid

Frequently Asked Questions

What is FIRE?

What is a FIRE number?

What is the 4% rule?

What are the FIRE variants?

Is FIRE realistic for most people?

Sources & further reading

Related Calculators

Retirement Savings Calculator

401(k) Calculator

Compound Interest Calculator

Pension Calculator

72(t) SEPP Calculator

457 Plan Calculator

Inputs

Results

Year-by-Year Breakdown