What Is FIRE?

FIRE stands for Financial Independence, Retire Early. The core idea is dead simple: save aggressively while you're young, build up a pile of investments large enough to cover your living expenses forever, then stop working — or at least stop working for money.

Honestly, a lot of people overcomplicate this. The math is straightforward: if you need $40,000 a year to live, and you follow the 4% rule, you need $1,000,000 invested. That's it. The hard part isn't the calculation — it's the discipline to save and the patience to let compound interest do its thing.

The 4 Types of FIRE

Lean FIRE

Lean FIRE is for people who are willing to live on a tight budget in exchange for freedom. Think $30,000-$50,000 annual expenses. No fancy cars, no eating out five times a week, maybe living in a cheaper country. The trade-off is real — you reach FIRE faster because you need less, but your lifestyle in retirement is also leaner. It works well for single people or minimalist couples.

Personally I think Lean FIRE gets a bad rap. People assume it means deprivation. But honestly a lot of Lean FIRE folks I've talked to say they're happier post-FIRE than they ever were spending money on stuff they didn't need.

Coast FIRE

Coast FIRE is the most interesting concept to me. The idea: you've saved enough that if you never contributed another dollar, the compound growth would get you to your full FIRE number by retirement age. So you can "coast" — take a lower-paying job you actually enjoy, work part-time, or pursue passion projects, because the heavy lifting is already done by your existing savings and time.

The calculator shows you your Coast FIRE target — the lump sum you need right now to stop contributing and still reach full FIRE. A lot of people are surprised at how attainable this number is.

Fat FIRE

Fat FIRE is for people who want to retire early without cutting back. Annual spending of $80,000-$150,000+. You still follow the same 4% rule math, but the target number is much bigger — $2M to $4M depending on your lifestyle. Fat FIRE usually takes longer and requires higher income or longer saving periods.

If I'm being honest, Fat FIRE is the most common goal people actually want but the least common one they achieve. The spending creep is real — every time your income goes up, it's tempting to let your lifestyle go up with it.

Barista FIRE

Barista FIRE is the pragmatic middle ground. You retire from your corporate career but keep a part-time job — traditionally at Starbucks (hence the name), but really any flexible part-time work. This part-time income covers a portion of your expenses, so you need a smaller investment portfolio. Plus you get health insurance and social connections.

In the calculator, Barista FIRE assumes your part-time job covers about $20,000 of your annual expenses. It's probably the most realistic path for most people — you still get out of the rat race, but you don't have to live like a monk or have millions in the bank.

The 4% Rule — Does It Still Work?

The 4% rule comes from the Trinity Study (1998): if you withdraw 4% of your portfolio in the first year of retirement and adjust for inflation after that, your money should last at least 30 years. A $1M portfolio gives you $40,000/year.

There's been a lot of debate lately about whether 4% is still safe. Between inflation, lower expected returns, and longer retirement spans, some experts now recommend 3.5% or even 3%. I'd personally plan for 3.5% if you're retiring before 50 — better safe than running out of money at 75.

The calculator defaults to 4% but you can adjust the SWR up or down. Try 3.5% and watch how much more you need to save — it's a sobering exercise but an important one.

How To Use This Calculator

Start with your current age and your target retirement age. Enter your current savings and monthly contribution — be realistic here, underestimating is better than overestimating. The expected annual return matters a lot: 7% is a common long-term average for a stock-heavy portfolio, but past performance doesn't guarantee future results.

Your annual expenses in retirement are the single most important number. Not what you spend today — what you'll need in retirement. Tbh most people overestimate this. Without commuting, work clothes, and eating out for lunch, your expenses usually drop by 20-30%.

Toggle between the 4 FIRE types to see how your target changes. Lean FIRE uses your entered expenses directly. Fat FIRE doubles them. Barista FIRE subtracts part-time income. Coast FIRE shows what you need today to stop saving and still hit the target.

Final Thoughts

FIRE isn't about never working again. It's about having the option to work on your terms. The calculator gives you the numbers — but honestly the hardest part is what comes after: actually sticking to the savings plan for years or decades without burning out.

The best advice I can give: don't obsess over the exact number. Build the habit, automate your savings, check progress once a quarter, and get on with living your life. The math works if you let it.