Coast FIRE Calculator — Free Retirement Number (2026)

What Is Coast FIRE?

Coast FIRE is the point where you've saved enough that — even if you never contribute another dollar — your investment portfolio will grow to your full FIRE number by your target retirement age, through compound interest alone.

The name comes from the idea of "coasting" to retirement: you've done the hard work of saving aggressively in your early years, and now you can step off the gas. Your investments compound on their own while you shift to a lower-pressure lifestyle — perhaps lower-paying work you enjoy, part-time work, or just working less intensely.

Example: You want a $1,500,000 FIRE number and plan to retire at 60. If you're 35 now, you have 25 years for your money to grow. At 7% real return, any portfolio over ~$277,000 today will reach $1.5M by 60 — without adding a single dollar.

Coast FIRE vs. FIRE vs. Barista FIRE

Variant	What It Means
Full FIRE	Portfolio is at 25x expenses — retire immediately
Coast FIRE	Portfolio will reach FIRE on its own — stop contributing, keep working to cover current expenses
Barista FIRE	Part-time/lower-stress work covers living expenses; portfolio coasts to full FIRE
Lean FIRE	Retired on a minimal budget (25x reduced expenses)
Fat FIRE	Retired on a generous budget (25x high expenses)

Coast FIRE is often the first major FIRE milestone — and for many people, it changes their relationship with work permanently.

How to Calculate Your Coast FIRE Number

The Coast FIRE number is the present value of your full FIRE number, discounted back at your expected real return rate:

Coast FIRE Number = FIRE Number ÷ (1 + r)^n

Where:

FIRE Number = Annual expenses × 25
r = Expected real annual return (e.g., 0.07 for 7%)
n = Years until your target retirement age

Example:

Annual expenses: $60,000 → FIRE Number = $1,500,000
Current age: 32, retirement age: 62 → n = 30 years
Expected return: 7% real
Coast FIRE Number = $1,500,000 ÷ (1.07)^30 = $1,500,000 ÷ 7.612 = ~$197,000

If you have $197,000 saved at age 32, you've hit Coast FIRE — your portfolio will grow to $1.5M by 62 without another contribution.

What Happens After Coast FIRE?

Once you've hit Coast FIRE, you have options most people never get:

1. Shift to lower-paying work you actually enjoy. You no longer need a high salary to fund retirement savings — just enough to cover current living expenses.

2. Work part-time. Cut to 3 days a week, take contract work, or freelance. Your retirement is already funded.

3. Take career risks. Start a business, change industries, or take a sabbatical. The financial downside is limited since your future is secured.

4. Reduce stress. Many Coast FIRE adherents stay in their careers but negotiate differently — they'll turn down toxic projects and demand better treatment, knowing they can walk away.

The Key Variables

Expected Real Return Rate

Use 6–7% for a diversified equity portfolio (US and international stocks). This is the historical average after inflation. Be conservative: using 5% is prudent for long time horizons.

FIRE Number Accuracy

Your Coast FIRE number is only as accurate as your FIRE number. Make sure your annual expense estimate is realistic and includes healthcare, inflation-adjusted costs, and lifestyle expenses you expect in retirement.

Time Horizon

The longer your runway, the lower your Coast FIRE number. An extra 5 years of compounding cuts the required starting amount significantly. Starting early is the biggest advantage in the Coast FIRE framework.

Strategies to Reach Coast FIRE Faster

1. Front-load contributions early. Because of compounding, money saved in your 20s is worth far more than money saved in your 40s. $10,000 invested at 25 grows to ~$75,000 by 55 at 7%; the same $10,000 at 45 grows to only ~$20,000.

2. Maximize tax-advantaged accounts. 401(k), Roth IRA, HSA — tax-free or tax-deferred growth accelerates the journey significantly.

3. Increase income, keep lifestyle flat. Every raise that goes straight to investments can dramatically shorten the timeline to Coast FIRE.

4. Move to a lower cost area. Reducing expenses lowers both your FIRE number and current spending, making it easier to save aggressively in the early years.

The Coast FIRE Trap

One risk: lifestyle inflation after hitting Coast FIRE. Once you ease off contributions and shift to lower-paying work, it's tempting to increase spending — which raises your FIRE number and potentially pushes full retirement further out.

Before shifting gears at Coast FIRE, model your new expected lifestyle expenses and confirm your Coast FIRE number still works under those assumptions.

Coast FIRE Strategy in Depth

How Coast FIRE Provides Freedom

The appeal of coast FIRE is the flexibility it offers:

Retire at 40: Work until 40 while your investments grow, then stop working entirely
Reduce to part-time: Work part-time or freelance while your retirement fund grows on its own
Career change: Switch to meaningful work without full salary if you're coasting to retirement

Real-World Coast FIRE Scenarios

Example 1: The Early Starter

Save aggressively ages 25-35 ($15,000/year)
Reach $200,000 target (with 7% returns)
Coast ages 35-65 (30 years of growth)
At retirement: ~$1.5M (without saving another dollar)

Example 2: The Career Switcher

Build $300,000 by age 40 through good income
Coast ages 40-67 (27 years)
Switch to non-profit work at 40% current salary (income drop covered)
At retirement: ~$1.8M without increasing coast target

Common Coast FIRE Mistakes

Underestimating expenses: Plan for healthcare, inflation, activities
Overestimating returns: 7% average is reasonable; don't assume 10%+
Ignoring sequence of returns: Market crashes early in coast phase hurt long-term growth
Forgetting about catch-up: No contributions during coast phase limits flexibility

Coast FIRE vs. Other Strategies

Lean FIRE: More extreme savings, retire earlier but on less
Fat FIRE: Save even more, retire with higher lifestyle spending
Coast FIRE: Sweet spot for many—save moderately, stop early, spend freely

The beauty of coast FIRE is achieving optionality: you're not forced to work past 40, but you can if you want.

FAQ

Does Coast FIRE account for inflation? Yes — use a real (inflation-adjusted) return rate in your calculation. If nominal returns are ~9–10% and inflation is ~2–3%, real returns are ~7%. Your FIRE number should also be in today's dollars.

What if I still contribute after hitting Coast FIRE? Even small contributions after Coast FIRE accelerate your full FIRE date considerably. The calculator shows how additional annual contributions change your retirement date.

Can I hit Coast FIRE before paying off student loans or a mortgage? Yes. Coast FIRE measures investment portfolio only. You can be Coast FIRE while still carrying debt — though high-interest debt should generally be eliminated before heavy investing.

What return rate should I use? Use 6–7% real return for planning. Some use 5% for extra conservatism. Avoid using nominal returns without adjusting for inflation, or you'll underestimate how much you need.

Related Calculators

Fire Calculator • Retirement Calculator • Investment Calculator

Sources & References

Federal Reserve - Consumer Resources
CFPB - Consumer Resources
Federal Trade Commission - Money Matters

Disclaimer

This calculator is provided for educational and informational purposes only. It is not financial, legal, tax, or investment advice. The results are estimates based on the assumptions and inputs you provide.

Actual results may differ significantly due to:

Changing interest rates and market conditions
Taxes, fees, and charges not accounted for in the calculation
Individual circumstances and variables not captured by the calculator

Please consult with a qualified financial advisor, tax professional, or attorney before making any financial decisions. Past performance does not guarantee future results. Always verify important calculations independently before relying on them.

Frequently Asked Questions

What exactly is Coast FIRE?

Coast FIRE is the financial milestone where your existing investment portfolio is large enough that — with no further contributions — it will grow on its own to your full retirement number by your target retirement age. Once you hit Coast FIRE, you only need to earn enough to cover current living expenses, freeing you from the pressure of saving aggressively for the future.

What inputs does the Coast FIRE Calculator need?

The calculator typically asks for: your current portfolio value, your full FIRE number (the nest egg size needed to retire), your expected annual return rate, your current age, and your target retirement age. From these, it back-calculates the portfolio value needed today to coast to your goal, and tells you how far you are from that milestone.

How is the Coast FIRE number calculated?

The calculator uses the present value formula applied in reverse: it discounts your target retirement portfolio back to today using your assumed annual growth rate. Specifically, Coast Number = FIRE Target / (1 + r)^n, where r is the annual return rate and n is the number of years until retirement. If your current portfolio equals or exceeds that number, you have reached Coast FIRE.

What annual return rate should I use?

This is one of the most consequential assumptions in the calculation. Rather than asserting a specific rate, use a figure that reflects long-run historical real returns for your asset allocation, adjusted for inflation if you want results in today's dollars. More conservative assumptions produce a larger (harder to reach) Coast number, which is a prudent way to build in a margin of safety.

Does reaching Coast FIRE mean I can stop working entirely?

Not necessarily — Coast FIRE means you can stop contributing to retirement savings, but you still need to cover your day-to-day living expenses through income (work, side projects, a partner's income, etc.) until retirement age. It is a step toward full FIRE, offering more flexibility and lower stress rather than immediate financial independence.