Coast FIRE questions, answered

Coast FIRE means saving aggressively until compound interest alone can grow your portfolio to your full FIRE number by traditional retirement age. Once you hit that point, you can stop saving entirely — or save far less — and still arrive at retirement financially independent.

The name comes from the idea that your money is "coasting" toward the finish line on its own. You still have to work to pay for current expenses, but the savings grind is over.

Traditional FIRE: Save aggressively all the way to retirement, then stop working. Most aggressive version.

Coast FIRE: Save aggressively in early career, then stop or reduce savings by mid-career while compound growth carries you to your target. Less aggressive, more flexible.

Barista FIRE: A Coast FIRE variant where you cover most expenses with part-time or lower-stress work in the "coast" phase. The portfolio bridges whatever gap remains.

The three sit on a spectrum: how much do you keep saving after the coast point? Zero (Coast), some (Barista), all the way (full FIRE).

For most people saving 15–25% of income from their mid-20s with a reasonable income, the coast point arrives somewhere between 35 and 45. That sounds earlier than expected, but it tracks the math: a $200K portfolio growing for 20–30 years at 7% real returns becomes a $1M–$1.5M portfolio, and the FIRE number for a moderate spender is in that range.

The hard part is the front-loaded saving. Most people who don't reach coast status aren't failing on the math — they're failing on the savings rate in years 3–7, when lifestyle inflation starts and the compounding hasn't yet made the sacrifices feel worth it.

Your FIRE number is the portfolio size that lets you withdraw your annual expenses indefinitely. The standard rule of thumb is annual expenses × 25 (the inverse of the 4% safe withdrawal rate), but the right number depends on:

• Your actual spending, not your aspirational spending
• The withdrawal rate you want to use (3.5% is more conservative; 4% is the historical default; 5% is aggressive)
• Whether you expect one-time large expenses (a house, kids' college) that should be funded separately

The calculator lets you set your own withdrawal rate. Most people start at 4% and adjust if the resulting number feels unattainable or if they want a margin of safety.

Four numbers:

• Current invested assets — everything in taxable brokerage, Roth IRA, Traditional IRA, and 401(k) accounts. Don't include your home equity, emergency fund, or money you'll need in the next 3 years.
• Annual expenses — what you actually spend in a year, not what you earn. The post-tax number matters, not the pre-tax number.
• Expected return — default 7% (a long-run real estimate). Use a lower number if you're more conservative.
• Current age — the calculator projects to 65 by default; you can change that to any target retirement age.

The core calculation is the present value of a future number:

coast_number = FIRE_number / (1 + r)^years_to_retirement

where FIRE_number = annual_expenses / withdrawal_rate, and r is the expected real return. The result is the portfolio size you need today such that, with no further contributions, compound growth carries you to your FIRE number by retirement age.

If your current invested assets are at or above the coast number, you can stop saving and still hit your target. If they're below, the calculator shows how long until you reach the coast point at your current savings rate.

All numbers in the calculator are in nominal (today's) dollars for simplicity. What that means in practice:

• Your Annual Expenses input is your current spending power
• The 7% expected return is a long-run real return (after inflation)
• The 4% withdrawal rate is a traditional rule of thumb for portfolio sustainability

Over a 30–35 year horizon, a 7% real-return portfolio typically outpaces average inflation, so your purchasing power grows even if you don't save another dollar. That's the Coast FIRE advantage. If you'd rather use nominal returns (the historical S&P 500 average of ~10%), the compound interest guide walks through the difference.

The calculator shows two milestones:

• Coast point: when your portfolio reaches the present-value amount that will compound to your FIRE number by retirement age. Above this, you can stop saving entirely.
• Full FIRE point: when your portfolio itself equals your FIRE number. Above this, you can stop working entirely (in theory).

The gap between the two is the "coast window" — the years where your portfolio is large enough to coast but not yet large enough to retire. Most people fill that window with a mix of lower-stress work, sabbaticals, or selective career moves.

Yes — the calculator lets you set your own. A few reference points:

• 3.0–3.5% (very conservative): High margin of safety. Used by people who retired before 2007 and lived through 2008–2009 without portfolio damage.
• 4.0% (standard): Bengen's 1994 study. Historical safe withdrawal rate across 30-year retirements in US data.
• 4.5–5.0% (aggressive): Higher risk of running out, especially in retirement sequences with poor early returns. Often used with the assumption of flexible spending in downturn years.

Higher withdrawal rates reduce your FIRE number but increase sequence-of-returns risk. The safe withdrawal rate guide has the full background.

For Coast FIRE math, the account type doesn't matter — what matters is the total invested amount and the time horizon. But for tax efficiency, prioritize this order:

• 401(k) up to the match: Free money. Always capture the full employer match.
• Roth IRA (or HSA if eligible): Tax-free growth and tax-free withdrawal in retirement. Especially valuable if you expect to be in a higher tax bracket later.
• Remaining 401(k) up to the limit: Pre-tax contributions reduce current-year taxes.
• Taxable brokerage: No contribution limits, no early-withdrawal penalty, but dividends and gains are taxed each year.

The "Coast FIRE" label doesn't care which bucket your money is in. The IRS, however, does. The 401(k) early-withdrawal penalty is real — a Roth IRA is the more flexible Coast FIRE vehicle for most people.

This is the single biggest non-investment risk in early retirement. Options:

• ACA marketplace: If your income is low enough (Coast FIRE often qualifies), ACA subsidies can make coverage very affordable. This is the most common path.
• COBRA: Continue employer coverage for 18 months after leaving. Usually expensive and a bridge, not a destination.
• Spouse's plan: If your partner has employer coverage, this is often the simplest solution.
• Health sharing ministry or direct primary care: Non-traditional options that some early retirees use, but they aren't insurance and don't cover everything.

Model your expected ACA subsidies before finalizing your Coast FIRE plan. They're often the difference between "this works" and "this doesn't quite work yet."

Mathematically, yes — if your portfolio is already at or near your FIRE number. The compounding advantage of Coast FIRE is the time between reaching the coast point and retirement age. With 0–5 years of that window, the difference between Coast FIRE and traditional FIRE mostly disappears.

If you're over 60 and your portfolio is below your number, the strategy is closer to "save aggressively for a few more years, then traditional retirement" than "coast." That said, the progress tracker can show you exactly how many years of saving remain at your current rate.

Standard Coast FIRE allocation by age range:

• Ages 20–40: 90–100% equities. Time in the market is your main advantage.
• Ages 40–55: 70–80% equities, 20–30% bonds. Starting to preserve capital as the coast window narrows.
• Ages 55+: 60–70% equities, 30–40% bonds. Preservation becomes more important than growth.

These are starting points, not prescriptions. Your personal risk tolerance, other income sources, and how close you are to the coast point all matter. Most Coast FIRE plans keep a higher equity allocation for longer than the traditional glide-path suggests, because the time horizon is "until retirement" rather than "until I need this money next year."

You can claim at age 62 (reduced benefit), full retirement age (typically 66–67), or delay to 70 for the maximum benefit (about 8% per year of delay past full retirement age). In Coast FIRE, you may coast on your portfolio for years before claiming Social Security, which usually means delaying to 70 is the right call.

Whether to include expected Social Security in your FIRE number is a modeling choice. The conservative approach is to plan as if you'll get $0 — then Social Security is pure upside. The optimistic approach is to subtract expected Social Security income from your annual expenses when calculating your number. The right answer depends on your confidence in the program, your health, and your family longevity.

Re-run the calculator. The coast number scales with expenses, so a 20% increase in spending means a 20% higher coast number. If your portfolio is well above the original coast number, you have a buffer. If it's right at the line, a lifestyle change can knock you back below it.

This is one reason most Coast FIRE plans build in a margin: hitting 1.2–1.5× the coast number gives you room for life events (kids, a home purchase, a career change) without losing coast status. The progress tracker is the easiest way to monitor this over time.

That's the scenario the calculator's expected return assumption averages out. In practice, the math still works as long as you don't panic-sell and as long as your time horizon is long enough. A 40% drop followed by a recovery leaves you in roughly the same place 10 years later — but only if you stay invested.

The bigger risk is selling during a downturn to cover current expenses. That's why most Coast FIRE plans include 1–2 years of cash reserves outside the invested portfolio: to cover spending during a market crash without having to sell investments at a loss. Sequence-of-returns risk is real; cash buffer is the standard defense.