Coast FIRE Calculator

Coast FIRE is a specific financial independence milestone: you've accumulated enough in investments that — even without adding another dollar — compound growth will carry your portfolio to your full FI number by your target retirement age. You've done the hard savings work. Now you can coast.

What is Coast FIRE?

The standard FIRE goal is accumulating enough to sustain withdrawals indefinitely — your FI number. Coast FIRE asks a different question: do you already have enough saved that compound growth alone, without any further contributions, will get you there by a specific age?

The math is straightforward. If your FI number is $2.28M (at $80K/year spending and 3.5% SWR), and you have 15 years until you want to retire, you don't need $2.28M today. You need the present value of $2.28M discounted at your expected real return:

Why Coast FIRE matters for early retirement planning

Most people building toward early retirement are in an execution phase: save aggressively, max every account, watch the number grow. But somewhere along the way — often sooner than they expect — they cross the Coast FI threshold. They don't realize it because they're still running the same playbook.

Knowing you've coasted changes what decisions make sense:

• Career flexibility: A lower-paying but less stressful job fully covers your costs without touching investments. The portfolio keeps compounding.
• Part-time or consulting: Working 3 days a week earns enough to live on. Your savings rate drops to zero — but that's now fine.
• Geographic arbitrage: Moving somewhere with lower costs covers expenses with part-time or remote income. Investments compound untouched.
• Health and family: Taking a year off for family, health, or a major project. Portfolio keeps working.

The point is not to stop entirely (though you can). The point is that hitting Coast FI transitions you from "must maximize contributions" to "just cover current expenses." That's a meaningful reduction in financial pressure with no sacrifice to long-run outcome.

Coast FIRE vs. Barista FIRE vs. full FIRE

Many early retirees spend 3–7 years in a Coast or Barista phase before transitioning to full FIRE. This path reduces total years of high-savings-rate work, maintains structure and income, and often provides health insurance through part-time employment — a meaningful consideration before Medicare at 65.

What a fee-only advisor models that this calculator doesn't

The Coast FI calculation is clean math, but the real-world version is more nuanced. A specialist advisor will model:

• Account type mix: If your $1.1M is split across traditional IRA, Roth IRA, and a taxable brokerage, the after-tax path to $2.28M looks different for each. Roth conversions during the Coast phase can reduce the future tax drag on that growth.
• Sequence of returns: A 5% real return average doesn't mean 5% every year. A 35% crash in year 3 of your Coast phase (when you're not contributing to cushion it) sets back the compounding timeline. A bond tent or cash buffer strategy adjusts for this.
• Social Security: Even if you stop contributing to a W-2 job, Social Security credits stop accruing. An advisor can model the effect of lower lifetime earnings on your eventual benefit — and whether delaying to 67 or 70 makes sense given your Coast FI timeline.
• Healthcare: Dropping to part-time often means losing employer health coverage. ACA marketplace costs before 65 depend heavily on your modified AGI. During a Coast phase, you may be able to engineer a low MAGI year that qualifies for substantial subsidies — but this requires coordination with any Roth conversion activity.
• Withdrawal strategy: Once you actually retire, the order in which you draw down taxable, tax-deferred, and Roth accounts materially affects how long your portfolio lasts. This is separate from whether you hit Coast FI on the way there.