Every version of FIRE runs through the same basic calculation. Our FIRE overview covers it in detail. Take your expected annual spending. Multiply it by 25. That’s roughly your target portfolio, assuming a 4% starting withdrawal rate. The Lean FIRE vs Fat FIRE comparison doesn’t change that formula. It changes what you plug into it. Coast FIRE goes a step further and asks a different question entirely.

The labels matter less than people think. Someone’s “FIRE type” is really just a description of the spending and lifestyle assumptions behind their number. Knowing which one matches your goals changes your target. It also changes how long it takes to get there.

Lean FIRE means financial independence built around a minimal spending target. Think somewhere between $25,000 and $40,000 a year, depending on location and household size. Run that through the 25x rule, and you land somewhere between $625,000 and $1 million. That’s meaningfully smaller than most other FIRE targets.

The appeal is obvious. A smaller number means you reach it faster, sometimes in well under 15 years even on a moderate income, as long as your savings rate stays high. But the tradeoff is just as obvious. A budget that tight leaves little room for error. An unexpected home repair, a medical bill, a bad year in the market, any of these can strain the plan. It also leaves little room for the spending most people associate with an enjoyable retirement: travel, hobbies, dining out, gifts for family. Lean FIRE tends to suit people who are already naturally minimalist. It also suits people who plan to supplement their income with part-time work, rather than relying on the portfolio to cover everything.

Fat FIRE sits at the opposite end of the spectrum from Lean FIRE. It funds financial independence at a genuinely comfortable, sometimes upscale, spending level. Often $100,000 a year or more, with no real cutbacks compared to a typical high earner’s lifestyle. Run that through 25x, and the target climbs to $2.5 million or higher. Sometimes considerably higher, depending on the specific spending goal.

Reaching a number that large usually takes a high income, a long accumulation period, or both. Fewer people pursue this path simply because the math demands more. But it solves the core criticism people level at Lean FIRE. Nobody pursuing Fat FIRE has to choose between financial independence and the lifestyle they actually want. They get both, just later, or with a higher income funding the climb. This is the heart of the Lean FIRE vs Fat FIRE tradeoff: speed and simplicity against comfort and scale.

Coast FIRE breaks from the Lean FIRE vs Fat FIRE comparison in a meaningful way. It doesn’t ask “how much do I need to stop working.” It asks “how much do I need saved right now, so that compound growth alone carries me to a full retirement number by a normal retirement age, without adding another dollar.” Once you hit your Coast FIRE number, you can, in theory, stop contributing to retirement accounts entirely. Compound growth on what’s already there will still carry you to your target by 65.

This doesn’t mean you stop working altogether. Most people pursuing Coast FIRE keep working. They just shift what their income is for. Instead of funding retirement contributions, it covers current living expenses. That opens the door to lower-stress jobs, reduced hours, or a career change that pays less but suits them better. You calculate the number by working backward from a standard retirement target, using compound growth. It’s essentially the reverse of a typical savings projection: you solve for the starting balance, not the ending one.

Barista FIRE sits between Coast FIRE and full retirement. It describes having enough saved to cover most expenses through withdrawals. You keep working part-time to cover the gap that’s left. Often that part-time work also covers employer-sponsored health insurance, one of the more expensive line items in any early retirement plan. The name comes from the idea of working a lower-stress job, historically joked about as a barista position. You take it for the income and benefits, not out of financial necessity for full-time work.

Say three people each want to stop full-time work. Person A targets Lean FIRE, spending $35,000 a year. That lands on a target of $875,000. Person B targets Fat FIRE, spending $110,000 a year. That lands on a target of $2.75 million. Person C isn’t trying to fully retire yet. They’re 35, they’ve saved $300,000, and they want to know their Coast FIRE number: the amount that, left alone to grow for 30 years until age 65, reaches a standard $1.5 million retirement target without another dollar contributed.

Assume a reasonable long-term average return. Person C’s $300,000 at 35, growing untouched for 30 years, lands in the range of their $1.5 million target. In other words, they’ve effectively already “coasted” into financial independence for a traditional retirement age. That’s true even though they’re nowhere near able to stop working today. This is the specific value Coast FIRE captures that Lean FIRE and Fat FIRE don’t. It measures progress toward a future date, not readiness to stop right now.

The same lifestyle can cost wildly different amounts depending on where you live. That means the line between Lean FIRE and Fat FIRE isn’t fixed. It moves with geography. $40,000 a year might feel genuinely lean in a major coastal city, barely covering rent. That same $40,000 supports a comfortable, unremarkable life in large parts of the country with a lower cost of living. Some people pursuing FIRE plan around this directly. They intentionally relocate to a lower cost-of-living area, specifically to shrink their number. Some call this geographic arbitrage.

This matters most if you’re deciding whether Lean FIRE feels achievable or unnecessarily restrictive. Before you write off a target as too tight, check what that same annual spending actually buys where you plan to retire. Don’t assume a single national number applies evenly everywhere.

Lean FIRE carries the least built-in cushion. A tight budget, calculated down to a specific spending figure, leaves little room to absorb a bad market year, an unplanned expense, or a mistake in the original spending estimate. That’s why some people pursuing Lean FIRE keep a part-time income source in reserve, rather than relying entirely on the portfolio.

Fat FIRE generally carries more built-in slack. The spending target already assumes a comfortable lifestyle, so cutting back temporarily during a rough market stretch is more of an inconvenience than a threat to covering basic needs. Coast FIRE sits somewhere in between. The risk isn’t running out of money during retirement, since retirement hasn’t started yet. The risk is that your income dries up before the portfolio finishes compounding to its target. That’s why people pursuing Coast FIRE generally still want stable, if lower-pressure, employment during the coasting years.

Most people don’t pick one of these labels and stick with it forever. Your target shifts as your income, spending, and priorities change. Someone starting out on a lower income might work toward Lean FIRE, simply because it’s the number within reach. They might adjust upward later, toward something closer to Fat FIRE, as their career progresses. Someone with a stable, well-paying job who doesn’t want to fully stop working might find Coast FIRE or Barista FIRE fits their actual goals better than a full retirement target ever would.

The label matters less than the numbers underneath it. Run your own spending, income, and timeline. Don’t adopt someone else’s target just because the acronym sounds appealing. Our guide on how much money you actually need to retire walks through the underlying spending calculation in detail, no matter which FIRE variant you’re aiming for.

Our Retirement Calculator projects your balance forward based on current savings and contributions. It works for testing a Coast FIRE scenario just as well as a traditional one. Just check how your current balance grows if you stopped contributing today. For the withdrawal side, once you’ve reached whichever number you’re targeting, our 4% Rule guide and our piece on how long retirement savings actually last cover the mechanics of drawing the money back down safely.

None of these paths beats the others outright. Each one solves for a different tradeoff between spending, timeline, and how much traditional work stays in the picture. The right one is whichever tradeoff actually matches how you want to live, not the one with the most appealing name.