Barista FI vs Coast FI vs Lean FI vs Fat FI: Definitions and Numbers

Lean, Fat, Coast, and Barista FIRE are four different answers to two different questions: how big is your number, and do you keep working while you get there. Here's what each term means and where they actually differ.

Lean FIRE, Fat FIRE, Coast FIRE, and Barista FI get listed together as if they were four flavors of the same thing. They are not. They are answers to two completely different questions, and once you see which question each one answers, the whole vocabulary snaps into place.

The first question is how big your number is: how much you want to spend each year in retirement, which sets how large a portfolio you need. Lean FIRE and Fat FIRE live here. The second question is whether you keep working while you get there, and how hard. Coast FIRE and Barista FI live here. This guide defines all four clearly, then shows exactly where they differ.

Lean FIRE: the smallest number

Lean FIRE means retiring on a deliberately low annual budget, which lets you stop working with a smaller portfolio than most people assume they need. There is no official dollar cutoff. The idea is simply that your yearly spending is modest by choice - a paid-off home, a low cost-of-living area, few fixed obligations - so the pile of money required to fund it is correspondingly small.

Because your number scales directly with your spending, a lean budget produces a lean target. If you can live comfortably on a small annual budget, the amount you need to accumulate shrinks with it. The trade-off is thinner margin: a low-spend retirement has less room to absorb a surprise, so lean plans lean harder on flexibility.

Fat FIRE: the largest number

Fat FIRE is the mirror image. You plan for a comfortable or generous annual budget - travel, a bigger house, private expenses, real slack in the numbers - and accept that funding it requires a much larger portfolio. Where Lean FIRE optimizes for reaching the finish line sooner on less, Fat FIRE optimizes for not having to compromise on lifestyle once you get there.

The mechanics are identical to Lean FIRE. Same withdrawal math, same portfolio, same market history. The only thing that changes is the spending figure you multiply by, and therefore the size of the target. Lean and Fat are two points on one dial, not two different machines.

Coast FIRE: stop saving, keep working

Coast FIRE changes the question entirely. It is not about how big your number is; it is about how you get there. Coast FIRE is the point where the money you have already invested is large enough to grow into your full retirement target on its own, with no further contributions - so you stop adding new savings and just keep working to cover today’s bills while compounding finishes the job.

You are still employed and still earning. You have just taken the pressure off: the portfolio no longer needs your paycheck, only time. That distinction has its own mechanics and its own main risk, which we cover in depth in what is Coast FIRE - this guide only needs the one-sentence definition to place it against the others.

Barista FI: work part-time by design

Barista FI is Coast FIRE’s close cousin, with one deliberate difference. Under Coast FIRE you keep working roughly as before to cover your full current spending. Under Barista FI, you cut back to part-time or lower-income work on purpose, and your portfolio covers the gap your smaller paycheck no longer does.

The name comes from the archetype of a part-time job taken for the steady paycheck and, often, the health insurance rather than the career. The structural point is that a Barista FI portfolio is already doing part of the heavy lifting: it funds the slice of your spending your reduced income does not. That makes it a genuine middle stage between Coast FIRE, where earnings still cover all of today’s costs, and full FIRE, where the portfolio covers everything and you do not need to work at all.

What is actually different

Here is the part the four-way list usually misses. These terms sit on two separate axes:

• How big is the number? Lean (small) versus Fat (large). This is set entirely by your target spending.
• Do you keep earning while the portfolio grows? Full FIRE (no), Coast FIRE (yes, full income), Barista FI (yes, part-time income).

Because they are separate axes, they combine. You can coast toward a lean number or a fat one. You can plan Barista FI on a modest budget or a generous one. Lean and Fat tell you where the finish line is; Coast and Barista tell you how much you are still rowing while you approach it.

Illustrative only, not advice. The Lean and Fat figures apply the 25x rule (a 4% withdrawal rate) to an example $30k and $120k of annual spending: 25 x $30,000 = $750,000 and 25 x $120,000 = $3,000,000. Coast and Barista are strategies rather than fixed spend tiers, so their "number" depends on your timeline and how much income you keep. Your real figures depend on your own spending, return, and withdrawal assumptions - see the 25x rule for how the target is built.

How the numbers relate

The withdrawal math that turns spending into a target is the same for every variant, which is why Lean and Fat differ only by the number you feed in. A quick way to see it: at a 4% withdrawal rate, your full-FIRE target is roughly 25 times your annual spending, so halving your planned spending roughly halves your number. We do not re-derive that here because it has its own guide - see the 25x rule and, for where that 4% figure comes from and how often it actually held up, safe withdrawal rates across history.

Barista FI bends this in a useful way. Because part-time income covers a slice of your spending, your portfolio only has to fund the remainder. If your budget is a modest annual figure and a part-time job covers part of it, the portfolio is sized to the leftover, not the whole - so the invested number you need to walk away from full-time work can be meaningfully lower than a full-FIRE target on the same lifestyle. That is the whole appeal: you trade a smaller required portfolio for continuing to earn something.

Picking the words that fit you

None of these four is a rank, and none is a finish line you have to reach in order. They are a shared vocabulary for two honest choices: how much you want your future life to cost, and how long you want to keep earning while you fund it.

Decide the spending first, because that sets the size of the number, and Lean or Fat is just where your budget lands on that dial. Then decide how you want to approach it: keep earning at full tilt and let the portfolio compound (Coast), step down to part-time and let the portfolio cover the gap (Barista), or aim to stop working entirely. The most useful move is not to pick a label but to put your own numbers into a projection and watch what each choice does to your timeline and your odds.

Frequently asked