Coast FIRE Number by Age
How much you need invested at each age so compounding alone carries you to retirement. Get your number below, then see the full reference grid.
Your Coast FIRE number by age
Based on your inputs above, notice how much less you need the earlier you start:
| If you're this age… | You need invested today | Years to grow |
|---|
Coast FIRE reference grid
The amount you need invested today to coast to different FIRE targets by age 65, assuming a 4% real (after-inflation) return, the same default as the calculator above. Find your age and target lifestyle.
FIRE targets shown assume the 4% rule (spending × 25): $750k ≈ $30k/yr, $1M ≈ $40k/yr, $1.5M ≈ $60k/yr, $2M ≈ $80k/yr.
Why your Coast FIRE number rises with age
Compound growth is exponential, so time is the most powerful input. A dollar invested at 25 has 40 years to grow; at 45 it has only 20. That's why someone at 25 might need only ~$208k to coast to $1M, while someone at 45 needs ~$456k for the same target (at the calculator's default 4% real return). The lesson isn't "it's too late", it's that every year earlier dramatically lowers the bar.
Reading the table: the halving pattern
Scan any column of the grid from bottom to top and you'll see the same shape: the required amount doesn't fall in a straight line, it falls faster and faster the younger you are. That's the rule of 72 at work. Money growing at the grid's 4% real return doubles roughly every 18 years (72 ÷ 4), which means the amount you need today for the same target halves for every extra 18 years of runway. At a more optimistic 5% real assumption the doubling takes about 14 years, the pattern is the same, just compressed.
That's why a $1,000,000 target (a $40,000-a-year lifestyle under the 4% rule) asks so much less of a 25-year-old than a 45-year-old. The 25-year-old's dollars get roughly one extra doubling more than the 45-year-old's before age 65 — and one doubling means less than half the upfront money. Nothing about the younger saver is smarter or luckier, they've simply lent their money to compounding for longer.
What each milestone actually means
Coast FIRE at 25 means retirement is mathematically handled for the rest of your working life. With roughly $208,000 invested toward a $1M-by-65 target at a 4% real return, every paycheck from here on is for living, not for catching up. People who hit this usually did it with an aggressive early savings rate, and the payoff is four decades of career freedom.
Coast FIRE at 35 means the pressure phase is over just as life usually gets expensive. Around $308,000 toward the same target and the mortgage, kids and career pivots of your late 30s and 40s no longer compete with retirement saving, retirement is already funded, it just needs time.
Coast FIRE at 45 means you've banked roughly $456,000 toward that target and can stop contributing twenty years before you retire. That's often the difference between grinding out a stressful final stretch and downshifting into work you actually like, the theme of the full Coast FIRE guide.
Whatever your age, the move is identical: find your row, compare it with what you've invested, and if you're short, treat the gap, not the whole FIRE number, as the thing to close.
Frequently asked questions
What if I'm past 50, is Coast FIRE still worth checking?
Yes, the bar is higher but the question is the same. With ten or fifteen years to a traditional retirement age, growth still does real work, and many people in their 50s discover they already passed their Coast FIRE number without knowing it. If you haven't, the levers are retiring a little later or coasting toward a leaner spending target, see the Lean FIRE calculator for what a smaller budget does to the target.
Does my target retirement age matter more than my current age?
What actually drives the number is the gap between the two, the years your money has to grow. Retiring at 70 instead of 65 gives your portfolio five more years of compounding, which lowers today's requirement in exactly the same way being five years younger would.
Can I keep contributing after I reach my Coast FIRE number?
Of course, Coast FIRE only tells you that further saving is optional, not forbidden. Anything you add after crossing the line pulls your retirement date earlier or raises your retirement budget. Many people keep saving at a relaxed pace and treat the coast number as their permission slip to stop stressing.