Coast FIRE: The Laziest Path to Financial Independence (and the Math That Makes It Work)
Coast FIRE: The Laziest Path to Financial Independence (and the Math That Makes It Work)
Most people who hear about the FIRE movement picture extreme frugality, 70% savings rates, and quitting your job at 35. That's one version. But there's another flavor that's actually more practical for most people, and it has a name that sounds almost too relaxed: Coast FIRE.
What Coast FIRE Actually Means
Coast FIRE is the point at which your existing investments, left alone, will grow enough to fund your retirement — without you contributing another dollar.
You're not retired. You're still working. But the pressure of saving is off. You've "coasted" to the finish line financially, even though you haven't crossed it yet.
The formula is surprisingly clean:
Coast FIRE Number = Target Portfolio / (1 + real_return)^years_until_retirement
Where Target Portfolio = Annual Spending / Safe Withdrawal Rate (typically 4%).
A Worked Example
Let's say you're 30, want to retire at 65, and expect to spend $40,000/year in today's dollars.
Target portfolio: $40,000 / 0.04 = $1,000,000 (in today's dollars)
Assuming a 4% real return (after inflation): $1,000,000 / (1.04)^35 = ~$253,000
Once you have $253K invested at age 30, compound growth alone handles the rest. You never need to save another dollar specifically for retirement.
Why This Matters
Coast FIRE isn't about quitting work. It's about removing the invisible pressure that most working adults live with — the feeling that every raise should go into savings, that every career decision has to maximize income, that you can't take risks because retirement hasn't been secured yet.
Once you hit your Coast FIRE number, you can:
Take a lower-paying job you actually enjoy
Drop to part-time
Start a business without the "what if I need that salary for retirement" anxiety
Just... stop stressing
The psychological shift is probably more valuable than the financial one.
The Math Most Online Calculators Get Wrong
When I started looking at Coast FIRE seriously, I tried a bunch of online calculators and found most of them broken in at least one of these ways:
No inflation adjustment. A Coast FIRE number in nominal dollars 30 years from now is meaningless.
Fixed return assumptions from the 1990s. Using 12% returns forever is how people get blindsided by sequence-of-returns risk.
Conflating Coast FIRE with other FIRE variants. Coast, Lean, Fat, and Barista FIRE are different strategies with different math. Treating them as one calculation helps nobody.
I ended up building my own tool at coastfirecalculator.io that handles all of these correctly. It's free, client-side only (so no financial data leaves your browser), and covers the main FIRE variants with real return rates and inflation adjustments.
You don't have to use that one specifically. But whatever calculator you do use, check that it:
Adjusts for inflation
Uses real (not nominal) return rates
Shows year-by-year projections, not just a single number
Distinguishes between Coast FIRE and other FIRE strategies
The Most Surprising Thing I Learned
Starting early is absurdly powerful. Look at how the Coast FIRE number scales with age (assuming $40K/yr spending, 4% real return, retire at 65):
25 years old: ~$185K
35 years old: ~$380K
45 years old: ~$675K
Ten years of compound growth at a 4% real return roughly doubles the number. This is the real argument for starting early — not moral virtue, just arithmetic.
Coast FIRE Isn't All-or-Nothing
You don't wake up one day "at Coast FIRE" and immediately quit your job. The real value is the mental model. Tracking how close you are to the point where saving becomes optional changes how you think about career risk, job satisfaction, and life decisions.
Even 30% of the way to your Coast FIRE number is meaningful. You can take more risk. You can prioritize work you like over work that pays. You can breathe.
If you want to run your own numbers, the tool is at coastfirecalculator.io — takes about 30 seconds, no signup required. And if you build your own, the formulas above should get you 90% of the way there.
Originally written for Ecency. Posted on the Hive blockchain where it lives forever — which feels appropriately on-brand for a topic about long-term thinking.