Is the 4% rule still safe?

The 4% rule is based on historical US stock and bond returns from 1926 to 1995. Some researchers argue that lower expected returns and longer retirements (due to early retirement) require a 3% or 3.5% withdrawal rate instead. Others point out that the 4% rule assumes no flexibility (never adjusting spending during downturns), which is unrealistic. A conservative approach: use 3.5% for planning, but be willing to adjust spending during bear markets.

Coast FIRE means you have saved enough that if you stop contributing and let your portfolio grow, it will reach your full FIRE number by traditional retirement age (e.g., 65). You can coast by taking a lower-stress job or working part-time because you no longer need to save aggressively. The OnSumo compound interest calculator can help you model when you reach Coast FIRE.

What is Lean FIRE versus Fat FIRE?

Lean FIRE means retiring on a minimal budget (e.g., $25,000-$40,000 per year), often requiring lifestyle sacrifices or geographic arbitrage (moving to a low cost-of-living area). Fat FIRE means retiring with a high budget (e.g., $100,000+ per year), requiring a much larger portfolio. Most people target something in between. Your FIRE number scales linearly with expenses: doubling your annual expenses doubles your FIRE number.

How do I account for healthcare costs before 65?

Healthcare is the biggest wildcard in early retirement. Before Medicare eligibility at 65, you need private insurance, ACA marketplace coverage, or a spouse's employer plan. Factor $500-$1,500 per month per person into your expense budget, depending on your health and deductible tolerance. Some FIRE retirees work part-time specifically to maintain employer health benefits.

What if I want to retire in my 30s or 40s?

Retiring in your 30s or 40s means your portfolio must last 50-60 years, not 30. The 4% rule may be too aggressive. Consider a 3% or 3.25% withdrawal rate to reduce the risk of running out. Alternatively, plan for some part-time income during early retirement (Barista FIRE) to reduce portfolio withdrawals during the critical first decade. Sequence-of-returns risk is highest when you retire into a bear market.

Should I include Social Security in my FIRE plan?

Social Security is a bonus, not a foundation. If you retire at 40, you are 27 years away from claiming benefits, and the program may change by then. Plan to be fully self-sufficient from your portfolio, and treat Social Security as a cushion that kicks in later. If you do factor it in, discount the benefit by 20-30% to account for potential program cuts.

What is the biggest risk to FIRE?

Sequence-of-returns risk: retiring right before a major bear market. If your portfolio drops 40% in year one or two of retirement and you keep withdrawing, you deplete the portfolio faster than historical averages predict. Mitigations: keep 2-3 years of expenses in cash or bonds (a cash buffer), be willing to cut spending during downturns, or delay retirement until after a recovery. The OnSumo net worth tracker can help you monitor portfolio health during retirement.

Can I FIRE with kids?

Yes, but kids increase your expense budget significantly (housing, food, education, healthcare, activities). If your pre-kid expenses are $40,000, expect $60,000-$80,000 with one or two children. Your FIRE number must account for the higher expenses, which may extend your timeline by several years. Some FIRE parents plan to return to work part-time once kids are school-age to reduce portfolio stress.

How does inflation affect my FIRE plan?

The 4% rule assumes you increase withdrawals by inflation each year to maintain purchasing power. If you retire on $40,000 per year and inflation averages 3%, you will need $52,000 in year 10 to buy the same goods. Your portfolio must grow enough to fund those inflation-adjusted withdrawals. If it does not, you either cut spending or risk running out. Use the OnSumo inflation calculator to model purchasing power erosion over your retirement horizon.

What is a good savings rate for FIRE?

50% or higher. The math is simple: if you save 50% of after-tax income, you can maintain your current lifestyle for one year in retirement for every year you work. Save 25%, and it takes roughly three working years to fund one retirement year. Save 75%, and one working year funds three retirement years. Savings rate is the single most important lever. The higher the rate, the faster you reach FIRE. The OnSumo take-home pay calculator can help you determine after-tax income for savings rate calculations.

FIRE Calculator (Financial Independence)

This calculator computes your FIRE number (the portfolio size needed to retire and live off investments) and projects how many years it will take to reach it at your current savings rate and expected return. It includes a year-by-year growth chart and a sensitivity table showing how changes in savings rate shift the timeline.

How does the FIRE Calculator work step by step?

This calculator determines how much you need to save to retire early using the FIRE (Financial Independence, Retire Early) framework. It takes your annual expenses, applies the 4% safe withdrawal rule (or a custom rate you specify), and calculates your FIRE number: the portfolio size that generates enough passive income to cover your expenses indefinitely. The tool also projects how long it will take to reach that number based on your current savings, contribution rate, and expected investment return.

When should you use the FIRE Calculator (Financial Independence)?

Use this calculator when you are planning early retirement, evaluating whether your current savings rate is sufficient, or deciding whether a lifestyle change (moving to a lower cost-of-living area, cutting expenses) would materially accelerate your FIRE timeline. The tool is especially valuable when you are considering a career change or sabbatical and need to know how much runway you have, or when you want to set a concrete savings target to track progress toward financial independence.

How do you read the FIRE Calculator (Financial Independence) results?

The FIRE number is the amount you need invested to retire. If your annual expenses are $40,000 and you use the 4% rule, your FIRE number is $1,000,000 ($40,000 / 0.04). The years-to-FIRE projection shows how long it takes to reach that number at your current savings rate. If the timeline is longer than you want, you can either increase your savings rate, reduce expenses (which lowers the FIRE number), or accept a higher withdrawal rate (which increases sequence-of-returns risk). The tool shows all three levers so you can model different paths.

What does a typical FIRE Calculator result look like?

Current portfolio: $50,000. Annual expenses: $40,000. Annual income: $80,000. Annual savings: $20,000. Expected return: 7% (inflation-adjusted). Safe withdrawal rate: 4%. FIRE Number: $1,000,000. Gap: $950,000. Savings rate: 25%. At these inputs, the portfolio crosses $1,000,000 at approximately year 21-22. Increasing the savings rate from 25% to 35% cuts roughly 5 years off the timeline.

What do the FIRE Calculator (Financial Independence) key terms mean?

FIRE (Financial Independence, Retire Early) is the movement and financial strategy of saving aggressively to retire decades before the traditional retirement age, typically by accumulating 25x annual expenses.

The 4% rule states that you can withdraw 4% of your portfolio annually in retirement with a high probability of not running out of money over 30 years, based on historical stock and bond returns.

Your FIRE number is the total portfolio size you need to retire, calculated as annual expenses divided by your safe withdrawal rate (typically 4%, or 25x expenses).

Savings rate is the percentage of after-tax income you save; it is the single most important variable in determining how fast you reach financial independence, more important than investment returns.

Frequently asked questions

Is the 4% rule still safe?
The 4% rule is based on historical US stock and bond returns from 1926 to 1995. Some researchers argue that lower expected returns and longer retirements (due to early retirement) require a 3% or 3.5% withdrawal rate instead. Others point out that the 4% rule assumes no flexibility (never adjusting spending during downturns), which is unrealistic. A conservative approach: use 3.5% for planning, but be willing to adjust spending during bear markets.
What is Coast FIRE?
Coast FIRE means you have saved enough that if you stop contributing and let your portfolio grow, it will reach your full FIRE number by traditional retirement age (e.g., 65). You can coast by taking a lower-stress job or working part-time because you no longer need to save aggressively. The OnSumo compound interest calculator can help you model when you reach Coast FIRE.
What is Lean FIRE versus Fat FIRE?
Lean FIRE means retiring on a minimal budget (e.g., $25,000-$40,000 per year), often requiring lifestyle sacrifices or geographic arbitrage (moving to a low cost-of-living area). Fat FIRE means retiring with a high budget (e.g., $100,000+ per year), requiring a much larger portfolio. Most people target something in between. Your FIRE number scales linearly with expenses: doubling your annual expenses doubles your FIRE number.
How do I account for healthcare costs before 65?
Healthcare is the biggest wildcard in early retirement. Before Medicare eligibility at 65, you need private insurance, ACA marketplace coverage, or a spouse's employer plan. Factor $500-$1,500 per month per person into your expense budget, depending on your health and deductible tolerance. Some FIRE retirees work part-time specifically to maintain employer health benefits.
What if I want to retire in my 30s or 40s?
Retiring in your 30s or 40s means your portfolio must last 50-60 years, not 30. The 4% rule may be too aggressive. Consider a 3% or 3.25% withdrawal rate to reduce the risk of running out. Alternatively, plan for some part-time income during early retirement (Barista FIRE) to reduce portfolio withdrawals during the critical first decade. Sequence-of-returns risk is highest when you retire into a bear market.
Should I include Social Security in my FIRE plan?
Social Security is a bonus, not a foundation. If you retire at 40, you are 27 years away from claiming benefits, and the program may change by then. Plan to be fully self-sufficient from your portfolio, and treat Social Security as a cushion that kicks in later. If you do factor it in, discount the benefit by 20-30% to account for potential program cuts.
What is the biggest risk to FIRE?
Sequence-of-returns risk: retiring right before a major bear market. If your portfolio drops 40% in year one or two of retirement and you keep withdrawing, you deplete the portfolio faster than historical averages predict. Mitigations: keep 2-3 years of expenses in cash or bonds (a cash buffer), be willing to cut spending during downturns, or delay retirement until after a recovery. The OnSumo net worth tracker can help you monitor portfolio health during retirement.
Can I FIRE with kids?
Yes, but kids increase your expense budget significantly (housing, food, education, healthcare, activities). If your pre-kid expenses are $40,000, expect $60,000-$80,000 with one or two children. Your FIRE number must account for the higher expenses, which may extend your timeline by several years. Some FIRE parents plan to return to work part-time once kids are school-age to reduce portfolio stress.
How does inflation affect my FIRE plan?
The 4% rule assumes you increase withdrawals by inflation each year to maintain purchasing power. If you retire on $40,000 per year and inflation averages 3%, you will need $52,000 in year 10 to buy the same goods. Your portfolio must grow enough to fund those inflation-adjusted withdrawals. If it does not, you either cut spending or risk running out. Use the OnSumo inflation calculator to model purchasing power erosion over your retirement horizon.
What is a good savings rate for FIRE?
50% or higher. The math is simple: if you save 50% of after-tax income, you can maintain your current lifestyle for one year in retirement for every year you work. Save 25%, and it takes roughly three working years to fund one retirement year. Save 75%, and one working year funds three retirement years. Savings rate is the single most important lever. The higher the rate, the faster you reach FIRE. The OnSumo take-home pay calculator can help you determine after-tax income for savings rate calculations.