Coast FIRE Explained: When You Can Stop Saving and Let Compounding Do the Work
What Is Coast FIRE?
Coast FIRE is the point where you’ve saved enough that your investments will grow to cover retirement on their own, even if you never invest another dollar.
Most retirement advice boils down to “save more, for longer.” Coast FIRE flips that. It asks: what’s the minimum I need to have invested today so that compound growth alone carries me to retirement by 65?
Once you hit that number, you’re “coasting.” You still need income to cover your living expenses, but you don’t need to save for retirement anymore. Every dollar you earn can go toward your life right now.
This is different from full financial independence, where your investments cover all your expenses immediately and work becomes optional. Most people will hit Coast FIRE long before they hit full FI.
How Coast FIRE Is Calculated
You need two things:
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Your full FI number. How much you need invested to retire. The standard method is the 4% rule: take your annual retirement expenses and multiply by 25. If you need $50,000 per year in retirement, your FI number is $1,250,000.
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How many years until retirement. The time you’re giving compound growth to work.
Then you discount your FI number back to today using an expected growth rate. At a 7% real (inflation-adjusted) return:
Coast FIRE Number = FI Number ÷ (1.07)^years until retirement
That gives you the amount you need invested right now for it to grow into your full FI number by retirement age, with zero additional contributions.
Coast FIRE Number by Age
Here’s what your Coast FIRE number looks like at different ages, assuming retirement at 65 and a 7% real annual return. Three spending levels are shown to cover a range of lifestyles.
| Current Age | Years to 65 | $40k/yr Spending ($1M FI target) |
$50k/yr Spending ($1.25M FI target) |
$60k/yr Spending ($1.5M FI target) |
|---|---|---|---|---|
| 25 | 40 years | $66,800 | $83,500 | $100,200 |
| 30 | 35 years | $93,700 | $117,100 | $140,500 |
| 35 | 30 years | $131,400 | $164,200 | $197,000 |
| 40 | 25 years | $184,200 | $230,300 | $276,400 |
| 45 | 20 years | $258,400 | $323,000 | $387,600 |
| 50 | 15 years | $362,500 | $453,100 | $543,700 |
| 55 | 10 years | $508,400 | $635,500 | $762,600 |
A 25-year-old targeting $50k/year in retirement spending needs just $83,500 invested today to be Coast FIRE. A 45-year-old needs nearly four times that. The younger you start, the less you need, because you’re giving compound growth more time to do the heavy lifting.
What Coasting Actually Looks Like
The table above shows when you could stop saving. But what actually happens if you do? We ran four scenarios through the Financial Independence Calculator to compare coasting (investing $0 going forward) against continuing to save.
| Scenario | Monthly Investing | Years to FI (if they coast) |
Years to FI (if they keep saving) |
Years Saved |
|---|---|---|---|---|
| 25-year-old, just getting started | $600/mo | 57 years (age 82) | 27 years (age 52) | 30 years |
| 28-year-old, been saving a few years | $1,000/mo | 42 years (age 70) | 22 years (age 50) | 20 years |
| 35-year-old, solid saver | $1,500/mo | 30 years (age 65) | 17 years (age 52) | 13 years |
| 40-year-old, late starter | $1,200/mo | 40 years (age 80) | 20 years (age 60) | 20 years |
Look at the 25-year-old. They have $20,000 invested. If they coast right now and stop contributing entirely, they won’t reach financial independence until they’re 82. If they keep putting in $600 a month, they reach FI at 52. That’s the same $600/month making a 30-year difference.
The 35-year-old is the most interesting case. They’ve already saved $160,000, so they’ve likely passed their Coast FIRE number. If they coasted, their money would grow to cover a traditional retirement at 65. That’s exactly what Coast FIRE promises. But by continuing to save $1,500/month, they reach full financial independence at 52, thirteen years ahead of schedule.
You can model your own version of this with the Financial Independence Calculator. Enter your current balances and contributions to see your FI date, then set contributions to $0 to see what coasting would cost you.
Coast FIRE Is a Milestone, Not a Finish Line
Coast FIRE is a useful concept, but it’s worth being honest about what it actually gets you: traditional retirement at 65. That’s the default. That’s what most people are already on track for if they save steadily in a 401k. The “coasting” part just means you’ve hit the minimum threshold to stop contributing and still get there.
The real question is whether traditional retirement at 65 is actually the goal.
Being an employee means you’re vulnerable. A company’s strategy can change on a whim. A new VP gets hired with a different vision that doesn’t include you. The economy tanks and your department gets cut. You can be great at your job and still lose it for reasons that have nothing to do with you.
And even when things are going well, working a traditional job means limited freedom. You have to ask permission to take days off. You can’t take a month off when you’re burned out. Your time isn’t really yours.
Full financial independence changes that. When your investments cover your expenses, work becomes optional. You can walk away from a bad situation without panic. You can take real risks, like starting a business or switching careers, because your survival doesn’t depend on the next paycheck.
That’s why hitting your Coast FIRE number should feel like progress, not like a finish line. It means the math is working. But the milestone that actually changes your life is full financial independence. And if you look at the 35-year-old scenario above, the difference between coasting to 65 and reaching full FI at 52 is just keeping up a savings rate they’re already maintaining. It’s worth noting that financial literacy itself correlates with dramatically higher net worth — understanding these concepts isn’t just academic, it’s a measurable advantage.
When Does It Make Sense to Actually Coast?
There are real situations where pulling back on savings is the right call:
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You need to downshift. If aggressive saving is running you into the ground, taking a lower-paying, lower-stress job while knowing retirement is covered is a reasonable trade. It beats burning out completely.
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You want to take a risk. Starting a business, going back to school, or making a career change is a lot easier when your retirement savings can grow on autopilot. Coast FIRE gives you room to make those moves.
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You’re well past your Coast number and need flexibility. If your investments have cleared your Coast threshold by a wide margin, pulling back on contributions to buy a house, pay off debt, or take a gap year makes sense.
In practice, most people who coast end up resuming contributions once their situation stabilizes. Once you’ve seen what continued saving does to your FI date, it’s hard to leave that on the table.
Coast FIRE vs. Other FIRE Milestones
Coast FIRE is one of several milestones on the path to financial independence:
| Milestone | What It Means | Example ($50k/yr spending) |
|---|---|---|
| Coast FIRE | Stop saving; growth alone funds retirement by 65 | $83,500–$635,500 (depends on age) |
| Lean FIRE | Retire now on a minimal budget (62.5% of target) | $781,250 |
| FIRE | Retire now at your target spending level | $1,250,000 |
| Fat FIRE | Retire now with a generous cushion (150% of target) | $1,875,000 |
Coast FIRE is usually the first one you’ll hit, and often by a wide margin. The Financial Independence Calculator tracks all four milestones automatically based on your inputs.
Calculate Your Coast FIRE Number
Your Coast FIRE number depends on your spending target, your age, and what you’ve already saved. The Financial Independence Calculator calculates your CoastFI milestone automatically alongside LeanFI, FI, and FatFI, and shows exactly when you’ll reach each one.
To see what coasting would cost you, run it twice: once with your actual monthly contributions, and once with everything set to $0.
FAQ
What is Coast FIRE? ▶
Coast FIRE is the point where you've invested enough that compound growth alone will grow your portfolio to cover retirement by age 65, without any additional contributions.
How do I calculate my Coast FIRE number? ▶
Take your FI target (annual expenses × 25), then divide it by (1.07) raised to the power of years until retirement. For example, a 30-year-old targeting $50k/year needs $1,250,000 ÷ (1.07)^35 = roughly $117,100 invested today.
Should I stop saving after reaching Coast FIRE? ▶
You can, but continuing to save, even at a reduced rate, protects against below-average market returns and gets you to full financial independence faster. Coasting gets you to traditional retirement at 65. Keeping your savings rate up can get you there 10-20 years earlier.
What's the difference between Coast FIRE and regular FIRE? ▶
Regular FIRE means your investments can cover all your expenses right now and you can stop working entirely. Coast FIRE means your investments will grow to that point by retirement age, but you still need to earn enough to cover current living expenses.
Does Coast FIRE account for inflation? ▶
Yes. When calculated with a "real" return rate (like 7% after inflation), all numbers are in today's dollars. Your Coast FIRE number represents purchasing power, not nominal dollars.
How long will my money last in retirement? ▶
Using the 4% rule, a portfolio is designed to last at least 30 years. Historical data shows it lasts indefinitely in most scenarios. The more you save beyond your Coast FIRE number, the larger your cushion.
Explore Your Numbers
- Financial Independence Calculator - See your CoastFI, LeanFI, FI, and FatFI milestones based on your actual numbers
- Monthly Budget Calculator - Figure out your real monthly expenses to set an accurate FI target
- Income Percentile Calculator - See where your income ranks in your area
- Net Worth Percentile Calculator - See where your Coast FIRE target puts you compared to others your age
Related Articles
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- When Do Earnings Peak? - Most income growth happens before 35, which is why front-loading your savings early matters so much.
How were these numbers calculated?
All scenarios were run using the Efficient Dollar Financial Independence Calculator. The calculator assumes a 7% real (inflation-adjusted) annual return on stock and index fund investments, a 2% real return on cash savings, and 3% annual wage growth on contributions. Coast FIRE numbers in the "by age" table use the formula: FI target ÷ (1.07)^years to 65. The scenario comparisons show actual calculator output with $0 contributions (coasting) vs. continued saving at the specified rates. FI targets are calculated using the 4% rule (25x annual expenses). All results are in today's dollars.
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