🌊 Coast FIRE Calculator
Find out how much you need saved today to coast to retirement — without contributing another dollar.
📊 Your Coast FIRE Breakdown
Coast FIRE Calculator: Your Complete Guide to Coasting Into Retirement
I’ve spent over a decade studying the FIRE movement — Financial Independence, Retire Early — and if there’s one concept that consistently surprises people with its elegance, it’s Coast FIRE. The idea is deceptively simple: save aggressively early, hit a specific number, and then let compound interest do the rest. No more mandatory saving. No more running the retirement rat race. Just living your life while your money quietly grows in the background.
But here’s what I’ve learned after interviewing hundreds of people pursuing financial independence: most of them don’t know their Coast FIRE number. They’re saving blindly, anxiously checking balances, without a concrete milestone to aim for. That’s exactly what our free Coast FIRE calculator at the top of this page is designed to solve.
What Is Coast FIRE? A Clear, Expert Definition
Coast FIRE is a milestone within the broader FIRE movement where you have saved enough money that — even without contributing another cent — your portfolio will grow to fully fund your retirement by your target retirement age, assuming a reasonable rate of return.
The term “coast” is the key metaphor here. Imagine you’re rowing a boat. You’ve been rowing hard — saving aggressively — and you’ve built up enough momentum. Now you can put the oars down and simply let the current (compound interest) carry you to shore (retirement).
Your Coast FIRE number is the amount you need in invested assets today so that compound growth alone gets your portfolio to your FIRE number (the total retirement nest egg) by your chosen retirement age.
The Four Types of FIRE: Where Coast FIRE Fits
🔥 Lean FIRE
Retiring on a very frugal budget, typically under $40,000/year. Extreme discipline required.
🌊 Coast FIRE
Save enough early, then stop — let compound interest carry you to a full retirement nest egg.
💰 Fat FIRE
Full retirement with a high income lifestyle — typically $100,000+ per year in expenses.
Coast FIRE occupies a uniquely achievable middle ground. It doesn’t require the extreme frugality of Lean FIRE or the massive portfolio of Fat FIRE. It rewards early savers and makes the math of retirement dramatically more approachable.
The Math Behind the Coast FIRE Calculator
Understanding the formula helps you trust — and customize — your results. Here’s how our Coast FIRE calculator works under the hood:
Step 1: Calculate Your FIRE Number
Your FIRE number is how much you need in your portfolio at retirement to sustainably withdraw your desired annual income. Using the widely accepted 4% Safe Withdrawal Rate (SWR):
FIRE Number = Annual Retirement Expenses ÷ Safe Withdrawal Rate
Example: If you want $50,000/year in retirement: $50,000 ÷ 0.04 = $1,250,000
Step 2: Calculate Your Coast FIRE Number
Now we discount that FIRE number back to today’s dollars using compound growth:
Coast FIRE Number = FIRE Number ÷ (1 + Real Return Rate)^Years to Retirement
Where the real return rate = (nominal return − inflation). With a 7% return and 3% inflation, the real rate is approximately 4%. Over 35 years, the discounting effect is dramatic — you need far less today than you’d assume.
Step 3: Compare to Current Savings
If your current savings ≥ Coast FIRE Number → You’ve already coasted!
If your current savings < Coast FIRE Number → The gap tells you exactly how much more aggressive saving is needed.
How to Use This Coast FIRE Calculator
- Enter your current age – Be precise. Every year matters enormously in compound growth calculations.
- Set your retirement age – Default is 65, but FIRE pursuers often target 45–55. Adjust freely.
- Enter current savings – Include all invested assets: 401k, IRA, brokerage accounts, pension value. Exclude emergency funds and home equity.
- Set annual retirement expenses – How much do you want to spend per year in retirement, in today’s dollars? Be honest — most people underestimate.
- Expected annual return – A 7% nominal return is the widely used historical average for a diversified equity portfolio. Adjust conservatively if you prefer.
- Safe withdrawal rate – The classic 4% rule is a strong default. More conservative planners use 3–3.5%.
- Inflation rate – 3% is a common assumption; use 2.5–3.5% for most scenarios.
- Select your currency – USD, GBP, EUR, AED, or PKR.
- Click “Calculate My Coast FIRE Number” – See your full breakdown instantly, including a progress bar showing how close you already are.
Real-World Example: Meet Sara, Age 32
🧮 Coast FIRE Calculation Example
Sara’s Profile:
- Current Age: 32 | Target Retirement Age: 60
- Current Savings: $85,000
- Desired Annual Retirement Income: $55,000
- Expected Return: 7% | SWR: 4% | Inflation: 3%
FIRE Number: $55,000 ÷ 0.04 = $1,375,000
Real Return Rate: (1.07/1.03) − 1 ≈ 3.88%
Years to Retirement: 28
Coast FIRE Number: $1,375,000 ÷ (1.0388)^28 ≈ $483,000
Sara’s current savings of $85,000 vs. $483,000 target: She’s 17.6% of the way there. She needs to continue saving aggressively — but she has a clear, concrete target to aim for.
If Sara hits $483,000 by age 40 and stops contributing entirely, her portfolio — growing at 7% annually — will reach approximately $1,375,000 by age 60. Coast FIRE achieved.
Coast FIRE Number by Age: Reference Table ($50,000/year Retirement Goal)
Assuming 7% annual return, 4% SWR, 3% inflation, retirement at age 65. FIRE Number = $1,250,000.
| Current Age | Years to Retire | Coast FIRE Number | Monthly Savings Needed* |
|---|---|---|---|
| 25 | 40 | ~$175,000 | ~$365/mo |
| 30 | 35 | ~$211,000 | ~$585/mo |
| 35 | 30 | ~$255,000 | ~$1,060/mo |
| 40 | 25 | ~$308,000 | ~$2,140/mo |
| 45 | 20 | ~$372,000 | ~$5,200/mo |
| 50 | 15 | ~$449,000 | ~$18,000/mo |
*Monthly savings to reach Coast FIRE in 5 years from shown age, assuming $0 starting balance. Real figures vary. Use our calculator for your specific scenario.
📊 Portfolio Growth After Hitting Coast FIRE (Starting at $211,000 Age 30, Retiring Age 65)
Why Coast FIRE Is the Most Underrated FIRE Strategy
Having analyzed thousands of retirement projections over the years, I’d argue Coast FIRE is consistently underrated for three reasons:
1. It Massively Reduces Stress
Once you’ve hit your Coast FIRE number, you no longer need to save for retirement. Every dollar you earn beyond basic expenses is truly discretionary. The psychological relief of removing “must save for retirement” from your monthly obligations is enormous — and often underappreciated until you’ve experienced it.
2. It’s Achievable Far Earlier Than Most Imagine
Because compound interest is exponential, the Coast FIRE number for a 25-year-old targeting retirement at 65 is surprisingly small — often under $200,000. That’s a number many dedicated savers can hit in their late 20s or early 30s.
3. It Enables Career Flexibility
Post-Coast-FIRE, you can take lower-paying jobs in fields you love, start a business with reduced financial risk, volunteer, travel, or work part-time. The safety net is in place. The freedom is real.
Expert Tips to Reach Your Coast FIRE Number Faster
- Start as early as humanly possible. A 25-year-old needs to save roughly half as much as a 35-year-old to reach the same retirement outcome. Time is the most valuable variable in this equation.
- Maximize tax-advantaged accounts first. 401(k), IRA, Roth IRA — these accounts shelter your returns from taxation, accelerating compound growth dramatically.
- Use index funds. Low-cost, diversified index funds (S&P 500 or total market) have historically delivered the 7–10% returns that Coast FIRE planning relies on.
- Avoid lifestyle inflation aggressively. Every raise that goes into your investment account instead of a bigger apartment accelerates your timeline significantly.
- Recalculate annually. Markets move. Your expenses may change. Revisit your Coast FIRE number every 12 months using this calculator.
- Don’t stop at the number — build a buffer. I recommend targeting 10–15% above your calculated Coast FIRE number to account for sequence-of-returns risk and unexpected expenses.
- Account for Social Security or pension income. If you expect Social Security or pension payments in retirement, your required FIRE number may be significantly lower, making Coast FIRE more achievable than the raw calculation suggests.
Common Coast FIRE Mistakes (And How to Avoid Them)
Using Too Optimistic a Return Rate
A 10% return looks great in a bull market. But your 30-year average may be 6–7%. I always run Coast FIRE calculations at both 6% and 8% to understand the range. Our calculator defaults to 7% — a conservative, historically grounded choice.
Ignoring Inflation
$50,000 today will not buy the same lifestyle in 30 years. Always use real return rates (nominal return minus inflation) for your projections, or input an inflation rate in our calculator, which handles this adjustment automatically.
Forgetting Healthcare Costs
Especially for early retirees (under 65 in the US), private health insurance before Medicare eligibility can cost $500–$1,500/month. Build this into your annual retirement expenses estimate.
Celebrating Too Early
Markets fluctuate. Your portfolio dropping 30% in a bear market right after you “hit” Coast FIRE can push you back significantly. This is why I recommend a 10–15% buffer above your calculated number before declaring Coast FIRE achieved.
Coast FIRE vs. Traditional Retirement Planning
| Factor | Traditional Planning | Coast FIRE Strategy |
|---|---|---|
| Savings requirement | Save 10–15% throughout career | Save aggressively early, then stop |
| Flexibility milestone | None until retirement | Coast FIRE number — often in your 30s–40s |
| Career flexibility | Low (must maintain income) | High (work becomes optional) |
| Stress reduction | Gradual | Dramatic at Coast FIRE milestone |
| Inflation adjustment | Often overlooked | Built into real-return calculation |
| Requires a calculator? | ✅ Yes | ✅ Absolutely essential |
Frequently Asked Questions About Coast FIRE
Your Financial Freedom Journey Starts With One Number
After years of covering personal finance, I’ve seen one pattern repeat itself: the people who achieve financial independence fastest are the ones who know their numbers cold. Not a vague sense of “I should save more” — but a specific, calculated target they pursue with clarity and consistency.
Your Coast FIRE number is that target. It’s the number that — once reached — fundamentally changes your relationship with work, money, and freedom. Use our calculator above to find yours. Recalculate when your expenses change. Build toward it with focus.
The math of compound interest is relentlessly patient. The only question is whether you’ll give it enough time and enough starting capital to work in your favor. The earlier you start, the more spectacular the result.
Calculate your number. Know where you stand. Start today.