Coast FIRE

By WealthIQ Editorial

Last Updated: March 2026

What Is Coast FIRE?

Coast FIRE is a variation of the broader Financial Independence, Retire Early (FIRE) movement. The core idea is deceptively simple: save and invest aggressively early in your career until your portfolio reaches a specific threshold — your “Coast FIRE number” — then stop contributing. From that point, you let compound interest do the heavy lifting over decades, carrying your balance to full retirement readiness by a traditional retirement age like 65.

Unlike traditional FIRE, which requires accumulating 25x your annual expenses and retiring as soon as possible, Coast FIRE doesn’t require you to retire early at all. You simply stop saving early. You still work, but your income only needs to cover current living expenses — not retirement savings. That shift can dramatically reduce financial pressure in your prime working years.

The name comes from the metaphor of coasting: once you’ve climbed the hill, you can take your foot off the gas and let momentum carry you forward.

How Coast FIRE Works: The Math

The calculation behind Coast FIRE relies on the future value formula:

Future Value = Present Value × (1 + r)ⁿ
Where r = annual return rate, n = years until retirement

To find your Coast FIRE number, you flip the equation:

Coast FIRE Number = Target Retirement Portfolio ÷ (1 + r)ⁿ

For example, if your target retirement portfolio is $1,000,000, you’re currently 30, plan to retire at 65 (35 years away), and assume 7% annual real returns:

Coast FIRE Number = $1,000,000 ÷ (1.07)³⁵ = $1,000,000 ÷ 10.677 ≈ $93,663

If you have $93,663 invested at age 30 and never add another dollar, it grows to $1,000,000 by age 65. That’s the power of a 35-year compounding runway.

Coast FIRE Numbers by Age

The table below shows how much you need invested today to reach $1,000,000 by age 65, assuming 7% average annual growth (roughly the historical real return of a diversified stock portfolio after inflation).

*Range reflects varying spending targets. Base case: $1M target at 7% real return. Monthly savings assumes starting from $0 with 7% growth over 5 years. Actual results will vary.

Real-World Example: Maya, Age 28

Maya is 28, earns $85,000/year, and wants to retire comfortably at 65. She estimates she’ll need $1.2 million (covering $48,000/year in expenses at a 4% withdrawal rate). Using the formula:

Coast FIRE Number = $1,200,000 ÷ (1.07)³⁷ = $1,200,000 ÷ 12.22 ≈ $98,200

Maya currently has $22,000 in her 401(k). If she contributes aggressively — roughly $1,500/month — she’ll reach $98,200 in about 3.5 years at age 31.5. After that, she can reduce or eliminate retirement contributions entirely, freeing up $1,500/month for travel, housing, or other goals, while her portfolio grows untouched to $1.2M by 65.

Coast FIRE vs. Traditional FIRE vs. Lean FIRE

It helps to understand Coast FIRE in context of other FIRE variants:

• Traditional FIRE: Accumulate 25x annual expenses, then retire immediately. Requires a much larger portfolio upfront (often $1.5M–$3M) and full work stoppage.
• Lean FIRE: Retire early on a very frugal budget, often under $40,000/year. High discipline required; vulnerable to healthcare and inflation shocks.
• Fat FIRE: Traditional FIRE but with a high income/expense lifestyle — typically $100,000+/year in retirement spending.
• Coast FIRE: Hit your number early, keep working to cover current expenses, retire at traditional age. Most flexible option for normal earners.
• Barista FIRE: Similar to Coast — work part-time for benefits and basic income, let portfolio grow. Often used interchangeably with Coast FIRE.

The Pros of Coast FIRE

• Dramatically reduced financial stress. Once you’ve hit your number, your future is secured whether or not you keep investing. That’s a profound psychological shift.
• More lifestyle flexibility in your 30s and 40s. You can take lower-paying but more meaningful work, go part-time, or move to a lower cost-of-living area without jeopardizing retirement.
• It doesn’t require extreme frugality forever. Unlike full FIRE, you only need to be aggressive for a defined sprint — not your entire life.
• Works with standard retirement accounts. 401(k)s, our complete Roth IRA guides, index funds — no special vehicles required.

The Cons of Coast FIRE

• Market risk over a long runway. A 30–40 year untouched portfolio is exposed to crashes, prolonged bear markets, and sequencing risk. A severe downturn in your 50s could delay retirement.
• Inflation uncertainty. $1 million in 2026 dollars may not be worth $1 million in 2061 dollars. Real return assumptions of 5–7% already factor in some inflation, but this varies.
• You still have to work. Coast FIRE doesn’t mean early retirement — you still need to earn enough to cover living expenses until 65 (or whenever you plan to stop).
• Social Security and healthcare gaps. If you reduce hours significantly, your Social Security benefit (based on lifetime earnings) may be lower than expected.
• Target numbers are estimates. Life changes: divorce, medical emergencies, job loss. Your $1M target may need revision.

How to Calculate Your Personal Coast FIRE Number

Follow these steps:

1. Estimate your annual retirement spending. A common starting point: 80% of your current income. Or use the 4% rule: target portfolio = annual spending ÷ 0.04.
2. Choose a retirement age. Most Coast FIRE adherents use 65, but you can use 60 or 55.
3. Assume a real return rate. 7% is the widely-used historical average for diversified equities after inflation. Conservative planners use 5–6%.
4. Apply the formula: Coast FIRE Number = Target ÷ (1 + r)ⁿ
5. Compare to current portfolio. The gap is what you need to save aggressively to close.

Free tools like ProjectionLab, cFIREsim, or even a simple spreadsheet make this calculation easy to model with different assumptions.

Where to Invest Your Coast FIRE Portfolio

For most people pursuing Coast FIRE, low-cost index funds inside tax-advantaged accounts are the optimal vehicle:

• 401(k)/403(b): Max out employer match first. After hitting Coast FIRE, you can reduce contributions to zero (though keeping some for the tax deduction may still make sense).
• Roth IRA: Contributions can be withdrawn penalty-free; growth is tax-free. Ideal for young earners in lower tax brackets.
• Taxable brokerage: Use after maxing tax-advantaged accounts. Choose tax-efficient index funds like VTI or VOO.

The investment mix during the accumulation sprint should be aggressive (80–100% equities). Once you hit your Coast FIRE number, many people maintain the same aggressive allocation since the 30+ year runway provides time to recover from downturns.

Is Coast FIRE Right for You?

Coast FIRE is well-suited for people who:

• Start investing in their 20s or early 30s and want to take the foot off the accelerator later
• Have high income now but expect lower income (or more flexibility) in midlife
• Want financial security without the extreme frugality required for traditional FIRE
• Are comfortable working until a normal retirement age, just not stressing about retirement savings

It’s less suited for those who want to fully retire before 50, need healthcare independent of employment, or have highly variable income that makes long-term projections difficult.

Bottom Line

Coast FIRE is arguably the most realistic branch of the FIRE movement for median earners. You don’t need to retire at 35. You don’t need to live on $30,000/year. You just need to sprint early, hit a math-based milestone, and then ease up. The compound interest engine takes it from there. For anyone in their 20s or early 30s reading this: the Coast FIRE number is much lower than you think — and the window to hit it is wide open.