The Ultimate Guide to Coast FIRE

Coast FIRE is one of the most practical variants of the Financial Independence movement. This guide explains it from first principles, traces its origins, and walks through the benefits, risks, and mistakes that matter most.

Definition

Coast FIRE is the moment when your invested assets — left to compound without another dollar of contributions — will grow into a complete retirement portfolio by your target retirement age. You still need to cover today's expenses, but the retirement clock can run on autopilot.

A brief history

The FIRE movement crystallized in the 2010s around blogs like Mr. Money Mustache and books such as Your Money or Your Life. Traditional FIRE demanded 50–70% savings rates and aggressive frugality. As the community grew, practitioners realized that compound growth does most of the heavy lifting if you front-load savings in your 20s and early 30s — and Coast FIRE was named.

Benefits

• Career flexibility. Take a lower-paying but more meaningful job.
• Parental runway. Step back during early-childhood years without panic.
• Reduced burnout. Aggressive saving has a shelf life; coasting is sustainable.
• Optionality. If you keep saving anyway, you simply retire earlier or richer.

Risks

• Sequence-of-returns risk. A deep crash shortly after you stop contributing damages the plan disproportionately.
• Return assumptions. Overestimating real returns by 1% can push retirement back a decade.
• Lifestyle inflation. "Coasting" income often creeps upward and crowds out the original plan.
• Healthcare. In countries without universal coverage, an unexpected event can force back into full-time work.

Worked examples

Example 1 — 30-year-old software engineer

Invested assets: $150,000. Real return: 6%. Retirement age: 65. Target spend: $45,000/yr at 4% SWR → $1.125M retirement target. Future value of $150k at 6% for 35 years ≈ $1.15M. Already Coast FIRE.

Example 2 — 40-year-old teacher

Invested assets: $120,000. Real return: 5%. Retirement age: 65. Target spend: $35,000/yr at 4% SWR → $875k. Future value of $120k at 5% for 25 years ≈ $406k.Gap of ~$469k — still requires contributions for several years.

Common mistakes

• Using a 10% nominal return instead of a 6–7% real return.
• Forgetting healthcare costs before Medicare/state coverage.
• Ignoring volatility — the median path is not the only path.
• Stopping contributions the day you hit the number, with no buffer.
• Not stress-testing against a lost decade.

Continue learning: Coast FIRE by Age · vs Other FIRE Strategies · Assumptions Explained