Lean FIRE Calculator : The Fastest Way to Retire Early

Tue Mar 21 2023

If you're like most people, retirement probably feels like a far-off dream. But what if you could retire early, and live life on your own terms much sooner than you think? That's the promise of Lean FIRE, a financial independence strategy focused on achieving financial independence as quickly as possible through aggressive saving and minimalism.

But is Lean FIRE right for you? In this article, I'll break down what LEAN FIRE is, the pros and cons of it, and show you how to calculate your Lean FIRE number.

So if you're ready to take control of your financial future and live life on your own terms, let's dive in!

LEAN FIRE Calculator

What is Lean FIRE?

Lean FIRE is a subculture of the Financial Independence Retire Early (FIRE) movement that emphasizes extreme frugality and minimalism to achieve financial independence and retire early. The term "Lean FIRE" was coined by one of my favorite FI/RE bloggers Mad Fientist in 2015. The goal of Lean FIRE is to reach a level of financial independence that allows one to cover basic living expenses through passive income and investments while maintaining a relatively simple and low-cost lifestyle.

Lean FIRE is all about simplifying your life and finding greater freedom and fulfillment. By focusing on reducing expenses , saving more, and investing wisely, FI followers of this philosophy build up a nest egg that allows them to retire early and pursue their most optimistic life.

But Lean FIRE is not for everyone. It requires a high level of focus and sacrifice in the short term to achieve long-term financial freedom. This could translate into downsizing your home, driving a beat-up car for a long period of time (hello 2004 Toyota Corolla!), and forgoing nights out on the town and possibly some travel.

While it's not for everyone, many people find the Lean FIRE lifestyle appealing because it allows them to live a simpler, more fulfilling life outside the traditional 9-to-5 grind.

How to Calculate Your LEAN FIRE number

If you're considering pursuing Lean FIRE, you may be wondering how long it will take to achieve your financial independence goal. The timeline for achieving Lean FIRE will depend on several factors, such as your current income, expenses, and investment strategy.

To get a rough estimate of how long it will take you to achieve Lean FIRE, you can use the LEAN FIRE calculator above. This calculator take into account your current income, expenses, and investment growth to project how long it will take you to reach financial independence.

Assuming a typical Lean FIRE retirement budget equal to your current expenses, you will need to accumulate 25 times your annual expenses in savings to achieve financial independence. For example, if your current annual expenses are $30,000, you will need to accumulate $750,000 in savings to achieve Lean FIRE.

Assuming an annual investment return of 7%, it would take approximately 17 years to accumulate $750,000 in savings if you're able to save $2,500 per month. However, if you're able to save more aggressively, such as $3,500 per month, it would take approximately 12 years to achieve Lean FIRE.

It's important to note that these are rough estimates, and your actual timeline for achieving Lean FIRE will depend on your personal financial situation and investment strategy. Additionally, pursuing Lean FIRE may require significant sacrifices and lifestyle changes in order to minimize expenses and save aggressively.

If you're serious about achieving Lean FIRE, it's important to create a solid financial plan and stick to it over the long-term. By making smart financial decisions and focusing on your long-term goals, you can achieve financial independence and retire early with a leaner, more minimalist lifestyle.

What does a potential Lean FIRE budget look like?

If you're pursuing Lean FIRE, your budget will likely look different than someone living a more conventional lifestyle. Lean FIRE followers aim to keep their expenses as low as possible and mainly spend on necessities, so they can save more and retire earlier.

Here are some typical expenses and budget categories for someone pursuing Lean FIRE:

  • Housing: This is often the biggest expense for most people, so those pursuing Lean FIRE tend to keep housing costs as low as possible. This might mean living in a smaller house, downsizing to a smaller apartment, or even living in a van or RV to save on rent. Living in low-cost-of-living areas (LCOLs) is a must!
  • Food: Eating out and buying expensive groceries can quickly eat into your budget. Those pursuing Lean FIRE often focus on cooking meals at home and buying food in bulk at COSTCO for example, to save money.
  • Transportation: Owning a car can be expensive, so those pursuing Lean FIRE often choose to live in an area with good public transportation, walk or bike to work, or opt for a more affordable car or even use a bike or a scooter. When we were pursuing LEAN FIRE, we drove our beat-up 2004 Corrolla for 10 years and with 200k+ miles on it.
  • Entertainment: Activities like traveling, dining out, and going to concerts or shows can be costly, so those pursuing Lean FIRE often find cheaper or free alternatives such as hiking, biking, reading, or spending time with friends and family.

Comparison of a Lean FIRE budget with a typical budget for someone living a more conventional lifestyle:

Compared to a more conventional lifestyle, a Lean FIRE budget might seem spartan. For example, someone living a conventional lifestyle might spend $1,500 per month on rent, $500 on groceries, $500 on transportation, $300 on entertainment, and $300 on other expenses, for a total of $3,100 per month.

Meanwhile, someone pursuing Lean FIRE might aim to spend only $500 per month on rent (living with roommates or in a small studio apartment), $200 on groceries, $100 on transportation, $100 on entertainment, and $100 on other expenses, for a total of $1,000 per month.

Tips for reducing expenses and maximizing savings to reach Lean FIRE goal faster:

If you're pursuing Lean FIRE, there are several things you can do to reduce expenses and save more:

  • Align your spending to what brings you joy and value and cut back on unnecessary expenses like dining out and buying expensive clothes.
  • Buy used or second-hand items whenever possible. Facebook Marketplace is a great place to save $$$!
  • Use public transportation or walk/bike instead of owning a car.
  • Cook meals at home and buy food in bulk to save money.
  • Downsize your living space or consider living with roommates to save on rent.

Remember, FIRE is a function of your monthly expenses and savings right so the more you can reduce expenses and save, the faster you can reach your Lean FIRE goal.

Fat FIRE Vs LEAN FIRE and Which is Right For Me?

While both Fat FIRE and Lean FIRE aim to achieve financial independence, the approaches and lifestyle goals are quite different.

Fat FIRE focuses on achieving a higher level of wealth and financial independence, which allows for a more luxurious lifestyle without the need for employment income. Fat FIRE followers typically aim to have a retirement budget that is at least 100k/year in expenses.

On the other hand, Lean FIRE aims to achieve financial independence with minimal expenses and a more frugal lifestyle. Lean FIRE followers typically aim to retire with a retirement budget equal to their current necessity expenses.

Here are some key differences between Fat FIRE and Lean FIRE:

  • Lifestyle goals: Fat FIRE is about achieving financial independence while maintaining a luxurious lifestyle, whereas Lean FIRE is about achieving financial independence with minimal expenses and a more frugal lifestyle.
  • Time horizon: Fat FIRE typically requires a longer time horizon due to the need to accumulate a higher amount of wealth, while Lean FIRE can often be achieved in a shorter time period due to the focus on minimizing expenses and saving aggressively.

In terms of how to achieve each type of FIRE, the strategies are similar but with different goals in mind. Both Fat FIRE and Lean FIRE rely on reducing expenses, increasing income, and investing in assets that generate passive income.

Ultimately, the choice between Fat FIRE and Lean FIRE depends on your lifestyle goals, personal values, and financial situation. For those who prioritize a more luxurious lifestyle and are willing to work longer to achieve financial independence, Fat FIRE may be the better option. However, for those who value a more minimalist and frugal lifestyle and want to achieve financial independence as quickly as possible, Lean FIRE may be the way to go.

The Pros and Cons of Lean FIRE

Like any financial independence strategy, Lean FIRE has its own set of pros and cons. Here are some of the main advantages and disadvantages to consider:


  • Achieving financial independence at a younger age: The biggest advantage of Lean FIRE is the ability to achieve financial independence and retire early, often in your 30s or 40s. Time is our most valuable resource so the more time you can spend living your best life even if it is on a tinier budget, the better.
  • Flexibility and control: Pursuing Lean FIRE gives you more flexibility and control over your lifestyle, allowing you to prioritize the things that matter most to you.
  • Minimalist lifestyle: By focusing on minimizing expenses and living a more minimalist lifestyle, pursuing Lean FIRE can lead to a more fulfilling and meaningful life, with less emphasis on material possessions.


  • Sacrifices and lifestyle changes: Achieving Lean FIRE requires significant sacrifices and lifestyle changes, including a frugal lifestyle.
  • Limited room for error: Pursuing Lean FIRE requires strict adherence to your financial plan, with little wiggle room for error or unexpected expenses. You can change this by changing your withdrawal rate in the calculator to a more conservative 3% and by also creating a sinking fund in your budget to save for planned expenses that occur throughout the year. This will increase the LEAN FIRE number and time it'll take you to get there but will give you more of a buffer.

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