What Is Coast FIRE? Your Complete Guide to the Two-Phase Strategy
You’ve probably heard of FIRE — Financial Independence, Retire Early. But within the FIRE community, there’s a specific variant that’s gaining serious traction, and for good reason. It’s called Coast FIRE, and it might be the most achievable path to financial independence that most people have never heard of.
What Is Coast FIRE?
Coast FIRE is a two-phase investing strategy. The core idea is simple:
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Phase 1 (Contribute): You invest aggressively for a defined number of years, building your portfolio to a specific target — your “coast number.”
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Phase 2 (Coast): Once you hit your coast number, you stop contributing entirely. You let compound interest grow your money to your full retirement goal, without adding another dollar.
The name comes from the second phase. Once you’ve reached your coast number, you’re “coasting” to retirement — you can reduce your saving rate, change careers, work part-time, or simply enjoy a lower-pressure financial life, knowing that your investments will carry you to your goal automatically.
What Is a Coast Number?
Your coast number is the amount you need invested today so that your portfolio — without any additional contributions — will grow to your retirement target by the time you retire.
For example: if you need $2 million by age 65, and you’re 35 today (30 years of growth), your coast number at an 8% return would be approximately $252,000. If you have $252,000 invested today, you can stop contributing entirely and reach $2 million by 65 through compound growth alone.
Coast Number = Target Amount ÷ (1 + annual return)^years to retirement
Or simply use the CoastVest calculator to run any scenario instantly.
The Two Phases, Explained
Phase 1: The Contribution Phase
This is the period when you’re actively investing money every month. Your goal in this phase is to reach your coast number as quickly as possible. The faster you get there, the sooner you can ease off.
During the contribution phase, your portfolio grows from two sources: your monthly contributions and compound investment returns. Both work together to accelerate your path to the coast number.
Phase 2: The Coast Phase
Once you hit your coast number, you enter the coast phase. This doesn’t mean you stop working — it means you stop needing to save for retirement. Your existing portfolio will do that work for you.
In the coast phase, your income is entirely your own. You could use it for living expenses, experiences, passion projects, or a different kind of work that you find more fulfilling but might pay less. Many Coast FIRE adherents use this phase to work part-time, start a business, or shift to nonprofit work.
Coast FIRE vs Regular FIRE
Regular FIRE aims to accumulate 25x your annual expenses (based on the 4% rule) before retiring completely. This requires a larger portfolio and typically means either very high income, very low expenses, or both.
Coast FIRE is different. You don’t need to accumulate your full retirement number today. You just need to reach your coast number, then let time do the rest. This makes it achievable for people who start investing in their 20s, even on average incomes.
| Regular FIRE | Coast FIRE | |
|---|---|---|
| Goal | Full retirement portfolio now | Coast number + time |
| Work required after | Optional | Often continue |
| Timeline | Depends on savings rate | Depends on start age |
| Best for | High earners/savers | Early starters, any income |
Who Is Coast FIRE For?
Coast FIRE tends to appeal to people who:
- Started investing young and want to know when they can relax
- Work in a job they don’t hate but wouldn’t choose if money weren’t a factor
- Want financial security without extreme frugality
- Are parents who want more time flexibility
- Have side interests they’d pursue if they didn’t need a high-paying job
It’s especially powerful for people in their 20s and early 30s who haven’t yet accumulated large savings but have time on their side. The earlier you hit your coast number, the longer the coast phase — and the more flexibility you gain.
How to Calculate Your Coast Number
You need three pieces of information:
- Your retirement target — typically 25x your expected annual retirement expenses
- Your retirement date — how many years until you want to retire
- Your expected annual return — typically 6–8% for long-term projections
Plug these into our Coast FIRE Calculator to see your coast number, how long it takes to reach it at your current contribution rate, and the full projection of your portfolio over both phases.
Enter your contribution years and invested years separately — see the exact moment you can stop. Try the Calculator Free →
The Psychological Power of Coast FIRE
Beyond the math, Coast FIRE offers something that standard retirement planning rarely does: a clear endpoint to mandatory saving.
Instead of feeling like you need to save forever, you’re working toward a concrete milestone. Once you cross it, you’ve genuinely changed your financial situation in a meaningful, permanent way. The pressure lifts. Choices open up. You can pursue work you find meaningful rather than maximally lucrative.
For many people, this shift — from “I need to save for 40 years” to “I need to hit my coast number” — is the thing that makes financial independence feel real and achievable rather than abstract and distant.
Getting Started
The most important step is simply knowing your coast number. Once you have that target, everything else — how much to save per month, how many years it will take, when you can ease off — becomes concrete and actionable.
Use the calculator, run the numbers, and find out where you actually stand. You might be closer to your coast number than you think.