Lean FIRE: financial independence on a smaller life

Lean FIRE applies the standard formula to a smaller life. You decide what you would spend if you trimmed hard, then multiply that by 25 instead of your current spending. Cut from €3,500 a month to €2,450 and the target falls from €1,050,000 to €735,000.

The formula

Reduced annual spending ÷ withdrawal rate.

Assumptions: 4% withdrawal rate, 8% growth before inflation, age 35 targeting 60. Stated in full in the methodology.

Worked example: €3,500 a month

This is not a round number. It is what my own living costs were at the point passive income covered them, which is the moment I would call being free.

Lean FIRE target€735,000

70% of today's spending at a 4.0% withdrawal rate.

And here is how long that takes, by what you put in every month.

Invested each monthTime to Lean FIRE
€1,00022 yr 3 mo
€2,00015 yr 6 mo
€3,50011 yrs

Look at what changes between those rows. The gap between them is a pay question, not an investing question, and that is the whole argument of this site. The calculator works out how much more you could be putting in without changing job.

Who it suits

People with low fixed costs, no dependants, and a genuine taste for a simple life.

What I think of it

Lean FIRE is the savings side of the equation taken to its end point, and it runs into the ceiling that side always has. There is a floor under your costs and you hit it fast. I saved 80% of my income for a year and it nearly broke me. The exit was not spending less. It was earning more, so the same freedom cost the same and arrived sooner without the misery.

Questions

How is Lean FIRE different from just being frugal?

Frugality is a habit. Lean FIRE is a target built on the assumption that the habit lasts for the rest of your life. That is the part worth thinking hard about.

What happens if my costs go up later?

The number moves with them, which is the risk. A plan sized to a very small life has little room in it for a child, an illness, or simply changing your mind.

The other eight

None of this is financial advice and I am not an adviser. Read what this is and what it is not.