Coast FIRE: How Much You Need Saved to Stop Contributing

Most people think of financial independence as a binary: either you have enough to retire or you don't. Coast FIRE is a milestone in between — the point where your investments, left alone with no further contributions, will grow to your retirement target by a specific age. Once you hit Coast FIRE, you only need to cover current expenses, not save for the future.

The Core Concept

Your Coast FIRE number is the amount you need invested today such that compound growth alone — with zero additional contributions — will reach your retirement number by your target retirement age.

Coast FIRE Number = Retirement Target / (1 + r)^(years to retirement)

Where:
r = annual real return (after inflation), typically 5-7%
years = target retirement age - current age

Example:

• Retirement target: $2,000,000
• Current age: 32
• Target retirement age: 60
• Years: 28
• Assumed real return: 7%

Coast FIRE Number = $2,000,000 / (1.07)^28 = $2,000,000 / 6.65 = ~$300,000

At 32, if you have $300,000 invested, compound growth at 7% real will turn it into $2M by age 60 — even if you never contribute another dollar.

What Changes at Coast FIRE

Before Coast FIRE: You need to save aggressively for the future. After Coast FIRE: You only need to earn enough to cover current living expenses.

This dramatically changes your employment calculus:

• You can take lower-paying jobs you enjoy
• You can work part-time
• You can start a business with lower guaranteed income
• You have a massive cushion for career risk

You're not retired — you still need income to live. But you're free from the pressure to maximize savings rate.

Coast FIRE Numbers by Age

Assuming a $2,000,000 retirement target at 65, at 7% real return:

The earlier you reach Coast FIRE, the less you need — time is the most powerful variable.

Calculating Your Coast FIRE Number

1. Determine your retirement spending: How much do you want to spend annually in retirement? Use your current expenses as a baseline and adjust.

2. Calculate your retirement target: Apply the 4% rule (25× annual spending).

   • $60,000/year needed → $1,500,000 target
   • $80,000/year needed → $2,000,000 target
   • $100,000/year needed → $2,500,000 target

3. Choose a retirement age: When do you want to be able to retire?

4. Apply the formula:

Coast FIRE = Retirement Target / (1 + real return rate)^years

Use 5-6% real return for conservative assumptions, 7% for moderate.

The Power of Starting Early

A 25-year-old with $133,000 invested reaches Coast FIRE toward a $2M/65 goal. But what does this mean practically?

If they contributed $1,000/month from 22 to 25, they likely have exactly that amount. Three years of aggressive saving → freedom from mandatory future saving for 40 years.

Compare to someone who starts at 35 needing $257,000 — they need nearly twice as much and have fewer years to reach it.

Coast FIRE vs Other FIRE Types

Coast FIRE is particularly useful as a milestone for people who enjoy working — it removes financial anxiety from career choices without requiring full retirement.

What to Do After Reaching Coast FIRE

You have options:

Continue saving: If you like your job and income, keep investing. You'll reach full FIRE faster and with more cushion.

Shift to "enough" saving: Reduce to saving only what you need for short-term goals (house down payment, etc.). No longer optimizing for maximum retirement contributions.

Change careers: Take that lower-paying role you actually want. Coast FIRE provides the safety net for career risk.

Reduce hours: Work part-time without fear of derailing retirement.

Start a business: The most common application — knowing your retirement is funded lets you tolerate the volatile income of early entrepreneurship.

Adjustments and Caveats

Inflation uncertainty: A 7% nominal return minus 3% inflation = 4% real. If inflation runs higher, adjust down.

Sequence of returns risk: Coast FIRE assumes steady compound returns, but real markets have crashes. A crash shortly after hitting Coast FIRE could require additional contributions to recover.

Contribution limits still matter: Even at Coast FIRE, maxing your 401(k) and IRA usually makes sense for tax advantages — Coast FIRE is about financial necessity, not optimization.

Healthcare: If you reduce work, account for health insurance costs not covered by an employer.

Lifestyle creep: Your retirement spending target should be honest. Many people underestimate how much they'll spend.

Tracking Progress to Coast FIRE

Calculate your current "Coasting Progress":

Coasting Progress % = Current Portfolio / Coast FIRE Number × 100

This gives you a more actionable number than total FIRE progress. Someone at 40% toward traditional FIRE might be at 80% toward Coast FIRE — a much more motivating picture.

Coast FIRE is often reached 5-10 years before full FIRE, making it a real intermediate milestone rather than just a theoretical concept.

The Psychological Value

Coast FIRE solves a specific problem: the feeling that you can never take career risk because you might derail retirement. Once you've hit Coast FIRE, that fear is mathematically gone. You could stop all retirement contributions tomorrow and still retire at your target.

This unlocks decisions people otherwise make poorly — staying in bad jobs for financial security, not taking calculated career risks, not starting projects they care about. Financial independence isn't binary, and Coast FIRE is the most actionable intermediate milestone in the journey.