Guide
ð What is Coast FIRE? The Complete Guide
Everything you need to know about Coast FIRE: how it works, how to calculate your number, who it's best for, and how it compares to other FIRE strategies.
Coast FIRE Explained Simply
Coast FIRE is the point where your invested assets are large enough that compound growth alone will carry your portfolio to your full FIRE number by retirement age -- without saving another dollar.
You still need to earn income for current expenses, but the hardest part -- building enough momentum for compound growth to take over -- is done.
Think of it like sailing: you've been rowing hard (saving aggressively). Coast FIRE is the moment you catch the wind (compound growth). You can put down the oars and the wind alone carries you to shore (your retirement number).
The Coast FIRE Formula
Step 1: Calculate your FIRE Number
FIRE Number = Annual Retirement Spending / Safe Withdrawal Rate
Example: $48,000 / 0.04 = $1,200,000
Step 2: Discount back to today
Coast FIRE Number = FIRE Number / (1 + real return)^years until retirement
Real return = (1 + nominal return) / (1 + inflation) - 1
Example: (1.07 / 1.03) - 1 = 3.88% real return
For a 30-year-old retiring at 65: $1,200,000 / (1.0388)^35 = $311,826
$48K
Annual spending
$1.2M
FIRE number
$312K
Coast FIRE number (age 30)
This means if you're 30 years old with $311,826 invested, you never need to save for retirement again. Compound growth alone will turn that into $1.2 million by age 65. Try our Coast FIRE Calculator to find your specific number.
Coast FIRE Number by Age
Assuming $48,000 annual retirement spending, 4% SWR, 7% nominal return, 3% inflation, and retirement at age 65:
| Current Age | Years to 65 | Coast FIRE Number |
|---|---|---|
| 25 | 40 | $259,076 |
| 30 | 35 | $311,826 |
| 35 | 30 | $375,380 |
| 40 | 25 | $451,892 |
| 45 | 20 | $543,988 |
| 50 | 15 | $654,854 |
| 55 | 10 | $788,278 |
The power of starting early is dramatic: a 25-year-old needs $259K while a 55-year-old needs $788K. That's the magic of compound growth working over decades.
Who is Coast FIRE For?
Want career flexibility
Switch to a passion project, nonprofit work, or lower-paying but more meaningful career.
Are burning out
Reduce stress by knowing retirement is funded, even if you take a pay cut.
Want to start a business
Take entrepreneurial risk knowing your retirement nest egg is growing on its own.
Are parents
Reduce work hours or take time off for family without jeopardizing retirement.
Value experiences over early retirement
Travel, learn, explore while still working enough to cover expenses.
Coast FIRE vs Other FIRE Strategies
*Based on $48K annual spending, 4% SWR, 30-year-old, retirement at 65
Risks and Limitations
No strategy is bulletproof. Here are the key risks to be aware of:
Sequence of returns risk
A prolonged bear market early on could delay when compound growth reaches your FIRE number.
Inflation uncertainty
Future inflation may be higher than assumed, reducing real returns.
Lifestyle inflation
Your spending needs may increase over time (kids, healthcare, housing).
No emergency buffer
If you stop saving entirely, you have no new contributions to absorb market downturns.
Healthcare costs
Before Medicare eligibility at 65, health insurance can be a major expense.
These risks don't invalidate the Coast FIRE strategy, but they suggest maintaining some savings as a buffer even after reaching your Coast FIRE number.
How to Reach Coast FIRE Faster
Maximize tax-advantaged accounts
401(k), Roth IRA, and HSA contributions grow tax-free or tax-deferred.
Increase income
Each raise can be directed toward investments.
Keep expenses low early
Living below your means in your 20s and 30s buys decades of freedom.
Invest in low-cost index funds
Minimize fees to maximize compound growth.
Consider a Roth conversion ladder
Plan early for tax-efficient withdrawals.
If you're a federal employee, check out our FERS Retirement Calculator to see how your pension fits into the FIRE equation.
Ready to find your number?
Use our free calculator to see when compound growth alone can fund your retirement.
Open Coast FIRE Calculator →