Coast FIRE Calculator — When Can You Stop Saving?
Calculate your Coast FIRE number — the amount you need saved now so compound growth alone will fund your retirement, letting you stop aggressive saving.
Coast FIRE is a milestone on the path to financial independence: the point at which your invested assets, left completely alone to compound, will reach your retirement target by traditional retirement age. Once you've "coasted," you can stop contributing new money to retirement and still finish with enough. You still work — to pay rent, groceries, insurance, and current lifestyle — but the pressure to save aggressively is gone. The math is pure compound interest run backwards: given a target number at a future age and an expected rate of return, what lump sum today grows to that target?
This free Coast FIRE calculator answers exactly that. Enter your current age, traditional retirement age (usually 65 or 67), target retirement portfolio (the 4% rule says 25× your desired annual spending), and expected real return (7% inflation-adjusted is the common US stock market assumption). The output is your Coast FIRE number — the minimum portfolio size today that will grow to your target without further contributions. Example: a 30-year-old targeting $1M at 65 with 7% returns needs roughly $94,000 invested today. A 40-year-old needs about $186,000 for the same target.
Why does Coast FIRE matter? Flexibility. Most people frame financial independence as binary — you're either working full-time or fully retired. Coast FIRE unlocks an intermediate state: you can take a lower-paying job you enjoy, switch to part-time, start a risky business, or take a sabbatical, without derailing retirement. It's the point where your 25-year-old self's aggressive saving finally buys your 40-year-old self's freedom. Contrast it with Barista FIRE (cover ongoing expenses with part-time work while portfolio grows), Lean FIRE (full retirement at a modest spending level), and Fat FIRE (full retirement at a luxury spending level). Coast is the earliest and most common milestone.
Quick answer: Coast FIRE is the amount invested today that compounds to your full retirement target without any further contributions. At age 30 targeting $1,000,000 by 65 at a 7% real return, your Coast FIRE number is about $93,700 — below that, keep saving; above, you can coast. This calculator finds your exact threshold and projected balance at retirement.
Inputs
Quick presetsYour age today. The younger you are, the smaller your Coast FIRE number — because compounding has more years to work.
The age you plan to stop working entirely. 65 and 67 are standard defaults; use 60 for a more conservative cushion.
Sum of all investable retirement assets: 401(k), IRA, HSA, taxable brokerage. Exclude home equity and emergency cash.
Portfolio size you need at retirement. Quick rule: multiply desired annual spending by 25 (the 4% safe withdrawal rule).
Expected real (inflation-adjusted) return. 7% for all-stock, 5% for 60/40, 4% for conservative. Do not enter nominal returns.
Results
How to use this calculator
Five inputs drive the projection. **Current age** and **retirement age** define the compounding window — longer windows produce smaller Coast FIRE numbers because compounding does more work. **Current savings** is the total of all retirement and investable accounts (401(k), IRA, brokerage, HSA); exclude home equity unless you plan to liquidate.
**Target retirement amount** is the portfolio size you need at retirement. The standard calculation uses the 4% safe withdrawal rule: multiply your desired annual retirement spending by 25. Need $60,000/year? Target $1.5M. Need $40,000/year? Target $1M. **Annual return** is your expected rate — use 7% for a stock-heavy portfolio adjusted for inflation, 5% for a 60/40 allocation, or more conservative numbers if you want a margin of safety.
The calculator returns your Coast FIRE number (what you need today), a yes/no flag on whether current savings have cleared the threshold, and the projected value of your current savings at retirement with no additional contributions. If projected value exceeds target, you've coasted.
Worked examples
Leah, 32, software engineer
Leah has $140,000 in her 401(k) and Roth IRA combined. She wants $1,250,000 at age 65 (to fund $50,000/year via the 4% rule) and expects a 7% real return. The calculator shows her Coast FIRE number is about $127,000 — meaning she's already coasted by $13,000. She can technically stop retirement contributions and still hit $1.25M at 65. In practice, she keeps contributing at a reduced rate (5% of salary for the 401(k) match) and redirects the rest to a house down payment, knowing retirement is handled.
Kenji, 45, mid-career pivot
Kenji has $210,000 invested and wants $1,000,000 at age 65. With 20 years to go at a 7% return, the calculator shows a Coast FIRE number of about $258,000 — he's $48,000 short. To close the gap, he either keeps contributing for another 4–5 years (roughly $10,000/year fills it), accepts a later retirement at 68, or dials target down to $800,000 (reducing retirement spending to $32,000/year). He chooses option one — four more years of contributions, then he coasts.
Aaliyah, 28, coasting to a creative career
Aaliyah has $85,000 in a Roth IRA and 401(k) after six years of aggressive saving at a tech job. She wants $1,000,000 at 65 to fund $40,000/year of modest retirement spending, and models a 7% real return. The calculator shows her Coast FIRE number is about $79,000 — she's already past it by $6,000. Projected value of her current savings at 65: roughly $1,075,000. She quits her corporate role, takes a $45,000/year job at an animation studio she loves, and stops retirement contributions entirely. Every dollar she earns now covers living expenses and creative projects — retirement is already paid for by her 22-year-old self's aggressive start.
Frequently asked questions
What's the Coast FIRE formula?
Coast FIRE Number = Target ÷ (1 + r)^n, where r is the annual return and n is years to retirement. For $1M at 65 with 7% returns starting at 30: $1,000,000 ÷ (1.07)^35 ≈ $94,000. That's the present value that compounds to $1M with no further contributions.
How is Coast FIRE different from Lean and Fat FIRE?
Lean FIRE = retiring fully at a modest spending level (e.g., $30K/year, $750K portfolio). Fat FIRE = retiring fully at a luxury level ($100K+/year, $2.5M+ portfolio). Coast FIRE is not about retiring — it's about stopping retirement contributions while still working to cover current expenses. You coast toward traditional retirement.
How does Coast FIRE compare to Barista FIRE?
Barista FIRE means working part-time (the 'barista' job traditionally covered health insurance) to cover current expenses while the portfolio grows untouched. Coast FIRE just means you don't need new retirement contributions — you could still work full-time. Barista is a lifestyle choice within Coast; Coast is the financial threshold that enables it.
What return rate should I use?
Conservative planning uses 5–6% real (inflation-adjusted). The US stock market has averaged ~7% real over the long run, but past returns aren't guaranteed. If you want a margin of safety, run the calculator at 5% — your Coast FIRE number will be meaningfully higher, but you're more insulated from a lost decade.
Should I include home equity?
Generally no. Home equity isn't easily liquidated at retirement unless you downsize or reverse-mortgage. Coast FIRE math is cleaner if you use investable assets only — 401(k), IRA, HSA, taxable brokerage. Count your home separately as housing security, not retirement fuel.
What if markets crash after I coast?
A 40% drawdown in year one reduces your projected 30-year balance by roughly 40% too. Sequence-of-returns risk matters less for Coasters than for retirees (you're not withdrawing), but you may need to resume contributions temporarily. Build a 10–20% margin of safety into your Coast number to absorb bad luck.
Does Social Security change the math?
Yes, if you count on it. Average US Social Security benefit is around $22,000/year, which in 4%-rule terms is equivalent to $550,000 of portfolio. Many Coast FIRE calculators let you subtract expected Social Security from your target. Younger workers may want to discount this to 70–80% given long-term funding uncertainty.
Can I un-coast?
Yes — Coast FIRE is a status, not a trapdoor. Markets, career, or life changes may mean your portfolio falls behind the projection. Recalculate annually; if projected value drifts below target, resume contributions until you're back on track. Some people cycle in and out of coasting multiple times over a career.