How to Use This Calculator
Enter your current age, how much you've already saved, and what you spend each year. The calculator does the rest — it figures out your FIRE number (the amount you need to retire), shows you when you'll hit it, and charts your progress year by year.
Want to see something interesting? Try bumping your savings rate up by just 5%. Watch how dramatically your FIRE date shifts. That's the power of the savings rate — it's the single biggest lever you have.
Here's what each field means:
Current Age is where you are today. The calculator uses this to project how many working years you have left.
Current Portfolio Value is everything you've already saved and invested — 401(k), IRA, brokerage accounts, all of it. Don't include your home equity or cash you need for emergencies.
Annual Expenses At Retirement is what you expect to spend each year once you stop working. If you're not sure, start with your current annual spending and adjust from there. Some costs drop in retirement (commuting, work clothes), while others rise (healthcare, travel).
Annual Income is your gross income before taxes. This determines how much you can save each year.
Current Annual Expenses is what you spend right now. The gap between your income and expenses determines your savings rate.
Savings Rate is the percentage of your income you're putting away. Most FIRE practitioners target 50-70%, but even 25-30% can get you there — it just takes longer.
Extra Monthly Savings covers any additional money you're setting aside on top of your regular savings rate. Side hustle income, bonuses, or one-time windfalls can go here.
Asset Allocation lets you set the mix of stocks, bonds, and cash in your portfolio. A more aggressive allocation (heavier on stocks) typically produces higher long-term returns but with more ups and downs along the way.
Expected Return is the annual growth rate you expect for each asset class. For stocks, historical long-term averages run around 10% before inflation. Bonds have averaged 4-6%. Cash sits around 2-4% [1].
Expected Inflation is how fast prices rise over time. The historical U.S. average is about 3% per year [2]. This matters because a dollar today won't buy as much in 20 years.
Income Growth Rate is how much your salary increases each year. The national average is roughly 3-4% [3]. As your income grows, your savings grow too (assuming you don't increase spending at the same rate).
What Is FIRE?
FIRE stands for Financial Independence, Retire Early. It's a movement built around one idea: if you save and invest aggressively enough, you can stop working for money decades before the traditional retirement age of 65.
The concept was popularized by Vicki Robin and Joe Dominguez in their 1992 book Your Money or Your Life, and it's gained massive traction since then [4]. The core principle is straightforward — save a large percentage of your income (often 50% or more), invest it wisely, and eventually your portfolio generates enough returns to cover your living expenses forever.
"Forever" is the key word. FIRE isn't about spending down your savings until they hit zero. It's about building a portfolio large enough that you can live off a small percentage of it each year while the rest keeps growing.
The FIRE Number: How Much Do You Actually Need?
This is the question everyone starts with. The answer comes from a simple formula:
FIRE Number = Annual Expenses x 25
If you spend $50,000 a year, your FIRE number is $1,250,000. If you spend $80,000, it's $2,000,000.
Why 25? Because 25 is the inverse of 4% — and the 4% rule is the foundation of FIRE math.
The 4% Rule
The 4% rule comes from the Trinity Study, a 1998 research paper by three finance professors at Trinity University [5]. They analyzed historical stock and bond returns going back to 1926 and found that a retiree who withdrew 4% of their portfolio in the first year of retirement, then adjusted that amount for inflation each year after, had a very high probability of not running out of money over a 30-year period.
Here's how it works in practice. If you have $1,250,000 saved, you withdraw $50,000 in year one (4% of $1.25M). In year two, you adjust that $50,000 for inflation — say 3% — so you'd withdraw $51,500. Your portfolio keeps growing from investment returns even as you're pulling money out.
The 4% rule isn't perfect. It was designed for a 30-year retirement starting at age 65. If you're retiring at 40, you're looking at a 50+ year retirement, so many FIRE practitioners use a more conservative withdrawal rate of 3% or 3.5% for extra safety.
The Savings Rate: Your Most Powerful Tool
Most people fixate on investment returns. But the variable that matters most in the early years? Your savings rate.
Here's why. If you earn $100,000 and save 10%, you're putting away $10,000 a year. At that rate, assuming 7% real returns, it takes roughly 51 years to reach financial independence [6].
Bump that savings rate to 25% and the timeline drops to about 32 years. At 50%, you're looking at about 17 years. At 70%, it's around 8.5 years.
The math works because a higher savings rate does two things simultaneously: it increases the money going into your portfolio and it reduces the annual expenses your portfolio needs to cover. Double benefit.
A Quick Example
Let's say you're 30 years old, earning $100,000, with $50,000 already saved.
- At a 25% savings rate ($25,000/year saved, $75,000/year spent), your FIRE number is $1,875,000. You'd reach it around age 52.
- At a 50% savings rate ($50,000/year saved, $50,000/year spent), your FIRE number drops to $1,250,000. You'd reach it around age 42.
- At a 70% savings rate ($70,000/year saved, $30,000/year spent), your FIRE number is just $750,000. You could hit it by age 37.
Notice something? Doubling the savings rate didn't just cut the timeline in half — it cut it by much more, because the target itself shrank.
Types of FIRE
Not everyone pursues FIRE the same way. Over the years, the community has developed several variations to match different lifestyles and goals.
Traditional FIRE is the standard approach: save 25 times your annual expenses, then retire. This typically means a savings rate of 50-70% over 10-20 years.
Lean FIRE is for people comfortable with a minimalist retirement — usually under $40,000 in annual spending. The portfolio target is smaller, but it requires genuine frugality. Some Lean FIRE practitioners relocate to lower cost-of-living areas or countries to make the math work.
Fat FIRE is the opposite end. It targets a comfortable or even luxurious retirement with $100,000 or more in annual spending. The trade-off? A much larger portfolio requirement, which means either a higher income, a longer timeline, or both.
Coast FIRE is the point where your existing investments are large enough that compound growth alone will carry them to your full retirement number by age 65 — without any additional contributions. Once you reach Coast FIRE, you only need to earn enough to cover your current expenses. You could switch to part-time work, take a lower-paying job you love, or simply stop stressing about your savings rate.
Barista FIRE (sometimes called "side-gig FIRE") is a hybrid approach. You've saved enough that your portfolio covers most of your expenses, but you supplement with part-time income. The name comes from the idea of working a low-stress job like a barista — though really, any part-time work counts. A big draw here is that some employers offer health insurance for part-time workers, which solves one of early retirement's biggest challenges.
What the Chart Shows You
The calculator generates a year-by-year projection with three components:
Portfolio (blue) is your total investment balance at the end of each year. You'll notice it curves upward — that's compound growth accelerating over time.
Contributions (green) represent the money you personally added to the portfolio each year. This is the part you control directly.
Returns (gold) are the investment gains your portfolio earned. In the early years, contributions dominate. Over time, returns take over. The crossover point — when your money earns more than you contribute — is one of the most motivating milestones on the FIRE journey.
Things This Calculator Doesn't Cover (But You Should Think About)
Healthcare Before Medicare
If you retire before 65, you won't have employer-sponsored health insurance or Medicare. You'll need to buy coverage through the ACA marketplace, use COBRA from your last employer, or get on a spouse's plan. Healthcare costs can run $500-$1,500+ per month for a family [7]. Factor this into your annual expenses estimate.
Taxes in Retirement
Different accounts have different tax treatments. Traditional 401(k) and IRA withdrawals are taxed as ordinary income. Roth withdrawals are tax-free. Capital gains from taxable accounts get their own rates. A good withdrawal strategy can save you thousands per year in taxes.
Market Volatility
This calculator uses fixed annual returns, but real markets don't work that way. Some years you'll be up 25%, others you'll be down 20%. The order in which returns happen (especially in the first few years of retirement) can dramatically affect whether your money lasts. This is called "sequence of returns risk."
Inflation
Prices rise over time. The calculator accounts for this in its projections, but keep an eye on your inflation assumption. Even small changes — from 3% to 4% — can significantly shift your FIRE date and required portfolio size.
Lifestyle Changes
Your spending in retirement probably won't match your spending today. Commuting costs disappear, but travel spending might increase. Kids might move out (reducing expenses) or you might want to help them financially. Build some flexibility into your numbers.
How to Use This Calculator Strategically
Test your savings rate. Bump it up by 5% and see how many years it shaves off your FIRE date. The results are usually surprising.
Play with the asset allocation. A 90/10 stock/bond split will show faster growth than 60/40, but with more risk. Find the balance that lets you sleep at night while still making progress.
Model a career change. Drop your income by $20,000 and see how it affects the timeline. This helps you understand the trade-offs if you're considering a less stressful (but lower-paying) job.
Plan for life events. Add $15,000 to your annual expenses for a new baby, or subtract $12,000 when the mortgage is paid off. See how these changes ripple through your projections.
Run best-case and worst-case scenarios. Try 10% returns (optimistic), 7% (moderate), and 5% (conservative). If you can retire under all three scenarios within an acceptable timeframe, you're in a strong position.
References
- Damodaran, A. (2024). Historical Returns on Stocks, Bonds and Bills: 1928-2023. NYU Stern School of Business.
- Bureau of Labor Statistics. (2025). Consumer Price Index Historical Data.
- Bureau of Labor Statistics. (2025). Employment Cost Index Summary.
- Robin, V., & Dominguez, J. (1992). Your Money or Your Life. Viking Penguin.
- Cooley, P., Hubbard, C., & Walz, D. (1998). Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable. AAII Journal.
- Collins, J.L. (2016). The Simple Path to Wealth. JL Collins LLC.
- Kaiser Family Foundation. (2025). Health Insurance Marketplace Calculator.
This calculator is for educational purposes only and does not constitute financial advice. Actual investment returns vary, and past performance does not guarantee future results. Consider consulting a qualified financial advisor for personalized guidance.