Coast FIRE Explained: Why I'm Not Trying To Save My Way To Retirement

I hit $180,000 in my investment accounts at 29 and immediately stopped maxing out my 401(k). My colleagues thought I'd lost my mind. But I'd discovered Coast FIRE, and it completely changed how I thought about money, work, and time.

Coast FIRE is the middle ground nobody talks about. It's not retiring at 35 with $2 million. It's not grinding until 65. It's hitting a specific number early, letting compound interest do the heavy lifting, and never saving another dollar for retirement if you don't want to.

Sound weird? It felt weird to me too. Until I ran the math.

What Coast FIRE Actually Means

Coast FIRE means you've saved enough that if you stopped contributing today, your money would still grow to cover a traditional retirement by age 65. You're "coasting" on compound interest alone.

The typical FIRE (Financial Independence, Retire Early) path says you need 25x your annual expenses invested. So if you spend $40,000 a year, you need $1 million. That's full FIRE. You can quit completely.

Coast FIRE is different. You might only need $200,000 at age 30. That's it. Then you stop saving for retirement entirely. Work part-time. Take a lower-paying job you actually like. Cover your current expenses and nothing more.

Here's why it works: time. A $200,000 portfolio at age 30, growing at 7% annually (the historical S&P 500 average after inflation), becomes $1.5 million by age 65. You contributed zero dollars for 35 years.

The Coast FIRE Calculator Nobody Had (So I Built One)

When I first learned about Coast FIRE in 2019, I spent hours with spreadsheets. How much did I actually need? What if I wanted to retire at 60 instead of 65? What if returns were 6% instead of 7%?

Every calculator I found online was either broken, oversimplified, or tried to sell me a course. So when I built BlackSquare, the Coast FIRE calculator was one of the first tools I added. Not because it's trendy. Because I needed it myself.

I built the Coast FIRE Calculator inside BlackSquare because I was tired of guessing. Try it free here and see your actual number in under 60 seconds.

Here's what makes a good Coast FIRE calculator:

• Current age and savings: Where you are right now
• Coast retirement age: When you want the money available (usually 60-65)
• Expected return rate: Realistic growth assumptions (6-8% is the sweet spot)
• Target retirement spending: How much you'll need annually in retirement
• Withdrawal rate: Usually 4%, based on the Trinity Study

The calculator tells you two numbers: your Coast FIRE number (how much you need today to stop saving) and your gap (how much more you need if you're not there yet).

Coast FIRE vs. Barista FIRE: What's The Difference?

People mix these up constantly. Here's the breakdown:

Coast FIRE: You've saved enough to coast to traditional retirement. You still need to cover current living expenses with income, but you're done saving for retirement. You could work full-time, part-time, or freelance. The point is you never have to save another dollar for age 65.

Barista FIRE: You've saved enough to cover most of your retirement, but you work part-time specifically for benefits (usually health insurance). The classic example is working at Starbucks for the health coverage while your investments grow. It's a subset of Coast FIRE with a specific purpose.

I'm technically on a Coast FIRE path right now. I hit my number at 31. I still work (I run BlackSquare), but I'm not funneling 30% of my income into retirement accounts anymore. I maxed out early. Now I invest in other things: real estate, the business, experiences I won't be able to do at 65.

The Math That Changed How I Work

Let me show you real numbers. This is how Coast FIRE works across different ages.

Age 25: You have $50,000 invested. At 7% annual growth, that becomes $761,000 by age 65. If you need $30,000/year in retirement (using the 4% rule), you'd need $750,000 total. You're basically there. Coast FIRE achieved at 25.

Age 30: You have $100,000 invested. At 7% growth, that's $1.07 million by 65. You can support $42,000/year in retirement spending. If that covers your lifestyle, you're done saving.

Age 35: You have $150,000 invested. That grows to $1.05 million by 65. Same $42,000/year support. But you have 5 fewer years of compound growth working for you.

The earlier you hit Coast FIRE, the more years of compounding you capture. This is why I pushed hard in my 20s. Every dollar I invested at 25 is worth $15 by the time I'm 65 (assuming 7% growth for 40 years). That same dollar invested at 35 is only worth $7.61.

Why Coast FIRE Isn't For Everyone (And That's Fine)

Coast FIRE has tradeoffs. Let's be honest about them.

You're betting on market returns. The standard Coast FIRE calculation assumes 6-8% average annual returns. Historically accurate over 30-40 years. But not guaranteed. If you hit a decade of flat markets early, your timeline shifts.

You're locked into a retirement age. If you want to retire at 50 instead of 65, Coast FIRE doesn't work. You need full FIRE numbers. Coast FIRE is specifically designed for people okay with a traditional retirement timeline, just without the traditional savings grind.

Healthcare is still your problem. Until you hit Medicare age (currently 65), you need health insurance. This is where Barista FIRE comes in. Or you pay out of pocket. Or you have a spouse with coverage. But it's a real consideration.

You still need income. Coast FIRE means you stop saving for retirement. You don't stop working entirely. You still need to cover rent, food, insurance, life. The freedom is in choice. You can take lower-paying work you love because you're not trying to save $30,000/year anymore.

How I Used Coast FIRE To Build BlackSquare

Here's the personal part. I worked in corporate finance for six years. Made good money. Saved aggressively. Hit my Coast FIRE number at 31 with about $220,000 invested.

That number gave me options. I didn't quit immediately. But I knew I could take risks. I spent a year building BlackSquare while still employed. When I finally left to do it full-time, I wasn't stressed about retirement savings. I was already set for 65.

Now I pay myself enough to cover expenses and reinvest profits into the business. I'm not maxing out a 401(k). I'm not hitting the $7,000 IRA contribution limit (2026 number, per the IRS). I'm building equity in something I own instead.

That's the Coast FIRE trade. I gave up the guaranteed tax advantages of retirement accounts for the flexibility to build wealth differently. Not for everyone. But it's working for me.

Using A Coast FIRE Calculator The Right Way

When you use a Coast FIRE calculator (like the one inside BlackSquare), here's how to think about the inputs:

Be conservative with returns. Don't plug in 10%. Use 6-7%. The S&P 500 has averaged about 10% nominal returns over the past century, but after inflation, it's closer to 7%. Use the real (after-inflation) number.

Overestimate retirement spending. If you think you'll need $40,000/year, plug in $50,000. Better to overshoot your Coast FIRE number than undershoot and have to go back to aggressive saving in your 40s.

Run multiple scenarios. What if you retire at 60? 62? 67? What if returns are 5%? 8%? See how sensitive your number is to assumptions. This helps you decide if you're comfortable coasting or if you want more buffer.

Account for Social Security (maybe). I don't include Social Security in my Coast FIRE calculation. I'm 32. Who knows what that system looks like in 30 years? But if you're 50 and can reasonably project benefits, factor it in. It lowers your Coast FIRE number.

The Coast FIRE Path I'd Take If I Started Over

If I were 23 again, here's exactly what I'd do:

Aggressive save for 7-10 years. Live below my means. Max out tax-advantaged accounts. Get to my Coast FIRE number as fast as possible. For most people earning $60,000-$80,000, that number is somewhere between $150,000-$250,000 depending on lifestyle.

Hit the number, then shift gears. Stop maxing retirement accounts. Redirect that cash flow into skills, side businesses, real estate, or just living better. The goal isn't deprivation. It's buying back your 30s and 40s.

Keep working, but on my terms. Take the job I want, not the one that pays most. Work part-time if that supports my lifestyle. Build something I own. The coast isn't about stopping. It's about choosing.

And I'd track it all in one place instead of juggling spreadsheets. That's why BlackSquare exists. Coast FIRE calculator, Freedom Number tracker, account aggregation. Everything you need to see if you're on track.

Coast FIRE isn't retirement at 35. It's freedom at 35 to design the next 30 years however you want. That's the real win.