Coast FIRE Calculator: When Can You Stop Saving?

Imagine reaching a point where you never have to save another dollar for retirement — and you'll still be financially independent by your target age. That's Coast FIRE. It's one of the most psychologically powerful milestones in the FIRE journey because it fundamentally changes your relationship with money. Once you're coasting, your only job is to cover current expenses. The future is already funded.

What Is Coast FIRE?

The term "coast" is deliberate: like a car that's built up enough speed to coast the rest of the way downhill without the engine running, a coasted portfolio has already been given enough fuel — years of contributions — that the destination is reached through momentum (compound growth) alone. What makes this different from simply "having savings" is the specific claim it makes: not just that you have money invested, but that the exact amount invested today, combined with a chosen number of years and a chosen, defensible return assumption, mathematically arrives at your full FIRE number without any further input from you.

Coast FIRE means you have enough money invested today that — without adding another dollar — it will compound to your full FIRE number by the time you want to retire. You "coast" to retirement on the growth already locked in.

The key insight: money invested at 25 has 40 years to grow before traditional retirement age. At 7% annual returns, $1 becomes $14.97 in 40 years. That incredible multiplier means you need far less invested today than you'll need at retirement.

How Your Assumed Return Changes the Number

The Coast FIRE formula is extremely sensitive to the return assumption, because it's raised to the power of however many years remain. Using Jordan's scenario — 30 years to retirement, $2,000,000 target — here's how the Coast FIRE number shifts across a realistic range of assumed returns:

Assumed Annual Return	Coast FIRE Number (30 years, $2M target)
4%	$616,637
5%	$462,755
6%	$348,220
7%	$262,734
8%	$198,755

Dropping the assumed return from 7% to 5% raises how much you'd need invested today by roughly three-quarters — from roughly $263,000 to $463,000 — because a lower return does dramatically less compounding work over 30 years. This is the practical reason a single "Coast FIRE number" isn't a fixed target for life: it depends entirely on which return assumption you trust, and that assumption deserves the same scrutiny you'd give any other major financial planning input.

Worked Example: The $2M Target

Let's use a detailed example. Jordan is 35, wants to retire at 65 (30 years away), and needs $2,000,000 at retirement (spending $80,000/year at 4% SWR). Assuming 7% average annual returns:

Coast FIRE Number = $2,000,000 ÷ (1.07)^30

= $2,000,000 ÷ 7.612 = $262,734

If Jordan has $262,734 invested today at 35 and never contributes another dollar, that portfolio will grow to approximately $2,000,000 by age 65. Jordan has officially hit Coast FIRE.

What if Jordan is only 25? Coast FIRE number = $2,000,000 ÷ (1.07)^40 = $2,000,000 ÷ 14.97 = $133,600. The earlier you reach Coast FIRE, the lower the number — because time is doing more of the work.

Coast FIRE Numbers by Age and Target

Assuming 7% annual returns and a retirement target age of 65:

Current Age	Years to 65	For $1M Target	For $1.5M Target	For $2M Target	For $3M Target
25	40	$66,800	$100,200	$133,600	$200,400
30	35	$93,700	$140,500	$187,300	$281,000
35	30	$131,400	$197,100	$262,734	$394,200
40	25	$184,200	$276,300	$368,400	$552,600
45	20	$258,400	$387,600	$516,800	$775,200
50	15	$362,400	$543,600	$724,800	$1,087,200

A 30-year-old with $187,300 invested has hit Coast FIRE for a $2M retirement target — even if they never contribute another dollar. For many people, this milestone arrives 10–15 years before full FIRE.

Real Returns: Why Inflation Belongs in This Math

Every number in this article so far uses a nominal return — the raw percentage before subtracting inflation. That's fine as long as your FIRE number and your spending target are also expressed in future, inflated dollars. But most people think about their $80,000/year spending target in today's dollars, which means the Coast FIRE math should really use a real (inflation-adjusted) return instead.

The historical long-run stock market return is often quoted around 10% nominal, but after subtracting roughly 2.5–3% average inflation, the real return is closer to 7% — which is exactly why 7% is the standard assumption used throughout this article: it's already meant to represent a real, inflation-adjusted return, so that a "$2,000,000" target means $2,000,000 of today's purchasing power, not $2,000,000 of future, inflated dollars that buy less. If you instead plug a nominal 10% return into the formula without adjusting for inflation, you'll significantly understate how much you actually need, because the calculation will assume your money is compounding faster in real terms than it actually is.

Why Coast FIRE Is Such a Powerful Milestone

Coast FIRE changes the game in several ways:

• It eliminates retirement savings stress. Once coasting, you only need to earn enough to cover today's bills. You can take a pay cut, change careers, work fewer hours, or move to a lower cost-of-living area without affecting your retirement trajectory.
• It unlocks career flexibility. If you hate your job but love your field at a different company that pays 20% less — you can make that move. The retirement math doesn't care.
• It creates a psychological shift. Many people report that hitting Coast FIRE is more liberating than hitting full FIRE, because it removes the pressure that distorts daily decision-making for years.
• It's achievable earlier than expected. For high earners or aggressive savers, Coast FIRE can arrive in their late 20s or early 30s — decades before traditional retirement.

Partial Coast FIRE: What to Do If You're Not Quite There Yet

Most people don't wake up exactly at their Coast FIRE number — they approach it gradually, and it's useful to know how much longer of "real" contributing is left before you can stop. Take Jordan again, but starting with $150,000 invested at 35 instead of the full $262,734 needed. That leaves a $112,734 shortfall against the 7% Coast FIRE target.

Contributing a modest $300/month on top of that $150,000 (still invested at 7%), Jordan closes the gap in approximately 6.4 years — reaching the Coast FIRE number around age 41, six years later than someone who hit it outright at 35, but still 24 years ahead of the traditional retirement age of 65. This is the realistic picture for most people: not a single moment of "coast now," but a partial-coast phase where a smaller, more sustainable contribution finishes the job before contributions can stop entirely.

Barista Coast FIRE: Earning a Little While Contributing a Little

Coast FIRE and Barista FIRE are often described as separate milestones, but many people move through a hybrid version of both: working part-time (the "barista" part) while still making small, non-essential contributions to retirement accounts (the "coast" part, but not fully passive). This hybrid approach hedges against the return-assumption risk discussed earlier — if markets underperform the assumed 7%, a household still adding even $100–$200/month has a buffer that a household that stopped contributing entirely does not.

The tradeoff is straightforward: full Coast FIRE gives maximum flexibility (you genuinely never need to contribute again), while a hybrid barista-coast approach sacrifices a small amount of that flexibility in exchange for a real cushion against the single biggest assumption in the entire calculation — that future returns will match the historical average used to get there.

What to Do With Income After Reaching Coast FIRE

Once you're coasting, your income only needs to cover current expenses. This creates genuine options most people never experience in their working lives:

• Work part-time: A 25-hour week at $25/hour generates $32,500/year — enough to cover a modest lifestyle in many cities.
• Switch to meaningful but lower-paying work: Teaching, non-profit work, freelancing, seasonal work — all become viable when you're not chasing a savings target.
• Start a business: You can take the income risk of entrepreneurship when the stakes are "can I cover expenses this month" rather than "can I fund my entire retirement."
• Keep saving aggressively: If you enjoy your work, continuing to save hard after Coast FIRE accelerates the arrival of full FIRE. Many people discover that Coast FIRE is a waypoint, not a stopping point.

Stress-Testing Your Coast FIRE Number

The Coast FIRE formula produces one clean number, but it's worth asking what happens if the assumed return doesn't show up. Take Jordan's $262,734 coast number, invested at 35 for 30 years, assuming 7%. If actual returns over that period average only 5% instead, the portfolio grows to roughly $1,135,521 by 65 — a shortfall of about $864,479 against the $2,000,000 target.

Now add the 20% buffer recommended in the risk callout below: instead of coasting at $262,734, Jordan waits until reaching $315,281 before declaring Coast FIRE. If the same disappointing 5% return shows up, that buffered amount grows to roughly $1,362,625 — still short of $2,000,000, but meaningfully closer than the unbuffered scenario. The buffer doesn't eliminate the risk of a below-average market decade; it reduces the size of the eventual gap, which is a more honest way to think about what a "safety margin" actually buys you in this calculation.

The practical implication isn't that Coast FIRE is unreliable — it's that a single point-in-time calculation, done once and never revisited, treats an assumption as a guarantee. Pairing the calculation with the periodic recalculation habit described in the FAQ below, and treating any buffer as risk reduction rather than risk elimination, keeps the plan honest about what it actually protects against.

How Asset Allocation Should Shift Once You're Coasting

While actively contributing toward Coast FIRE, most people hold a stock-heavy allocation, since new contributions keep flowing in regardless of short-term price swings — a market drop just means new money buys in cheaper. Once coasting, that dynamic changes: there's no more new money smoothing out the ride, and the entire portfolio needs to survive a specific number of years of market ups and downs on its own.

Many people coasting toward a distant target (10+ years away) keep a similarly stock-heavy allocation, since there's still enough time to recover from a downturn. As the target retirement age gets closer — inside 5–10 years — gradually shifting a portion of the portfolio toward bonds or other lower-volatility assets reduces the risk that a poorly-timed crash right before retirement permanently damages the plan. This is the same "glide path" logic used in target-date funds, just applied deliberately to a Coast FIRE portfolio instead of happening automatically inside a single fund.

Where this rebalancing happens matters too. Shifting allocation inside a 401(k) or IRA triggers no tax event — you're simply selling one fund and buying another inside a tax-advantaged wrapper. Doing the same shift inside a taxable brokerage account can trigger capital gains tax on any appreciated shares sold, which eats into the very portfolio you're trying to protect. A portfolio holding $150,000 of long-term gains inside a taxable account, for example, could owe $22,500–$30,000 in capital gains tax (at typical 15–20% federal long-term rates, before any state tax) just to execute the reallocation in one lump sum. Spreading a large reallocation across two or three tax years, or prioritizing the shift inside tax-advantaged accounts first, usually reduces this drag considerably.

Coast FIRE for Couples

For a couple, Coast FIRE math can be applied at the household level by combining both partners' invested assets and using a shared spending target — the formula itself doesn't change, only the inputs get combined. The added wrinkle for couples is that both partners often don't reach their individual Coast FIRE contribution point at the same career stage; one partner may be years ahead of the other in income or portfolio size. Most couples calculate Coast FIRE against the combined household portfolio and combined household spending target rather than running two separate calculations, since retirement spending in most households is shared rather than split cleanly down the middle. A couple with different individual retirement account types — one partner heavier in a 401(k), the other heavier in a taxable brokerage account — should also factor account accessibility into the plan, not just the combined total, since an early or semi-retirement plan depends on which accounts can actually be tapped before traditional retirement age.

Common Coast FIRE Mistakes

• Mixing nominal and real returns. As covered above, using a 9–10% nominal return with a spending target expressed in today's dollars understates the true Coast FIRE number significantly.
• Declaring "coasted" the exact moment the formula is satisfied, with no buffer. The risk callout below covers this — a 10–20% cushion above the calculated number provides real protection against a below-average market decade.
• Forgetting that spending targets change. A Coast FIRE number calculated against today's $80,000/year lifestyle needs to be recalculated if spending assumptions change — a new child, a paid-off mortgage, or a move to a different cost-of-living area all shift the target.
• Treating Coast FIRE as permanent once reached. Coast FIRE status depends on ongoing market performance matching the assumed return. It's worth re-checking the calculation periodically (annually is reasonable) rather than assuming a single calculation done years ago still holds.
• Ignoring taxes and account access rules. A Coast FIRE number invested entirely in a 401(k) may not be accessible penalty-free before 59½. Anyone planning to retire, semi-retire, or downshift income earlier than that needs at least some of the portfolio in accounts reachable before traditional retirement age.
• Overweighting a single employer stock position. If a large share of the coasted portfolio is concentrated in one company's stock — common with RSU-heavy compensation packages — the Coast FIRE math is effectively betting the whole plan on one company's future returns instead of the diversified market return the formula assumes. A gradual, tax-aware diversification plan out of a concentrated position is worth pursuing well before declaring Coast FIRE achieved.

Frequently Asked Questions

Does Coast FIRE mean I should stop contributing to retirement accounts entirely? Not necessarily. Reaching the Coast FIRE number means you technically no longer need to contribute for your original FIRE target to still be reached. Many people choose to keep contributing anyway — either to reach full FIRE sooner, or to build in the safety buffer discussed in the risk callout below.

Is Coast FIRE the same as Barista FIRE? No, though they're related. Coast FIRE describes a portfolio milestone — enough invested that no further contributions are required. Barista FIRE describes a lifestyle choice — working a lower-stress, often part-time job to cover current expenses. Many people reach Coast FIRE first and then choose Barista FIRE as the way they spend the years between coasting and full retirement.

What if I've already reached Coast FIRE and want to retire earlier than my original target age? The Coast FIRE formula is specifically calibrated to a chosen target retirement age. Retiring earlier than that age means the portfolio has fewer years to compound, so the amount needed today to "coast" to an earlier date is higher. Recalculating with the earlier age as the new target — using the same formula — gives the correct, larger number.

Does the Coast FIRE number account for Social Security? The basic formula shown throughout this article does not — it treats the full 25× spending target as something the portfolio alone needs to cover. For someone expecting meaningful Social Security income later in retirement, the true amount needed from the portfolio can be somewhat lower, since Social Security covers part of the retirement spending target instead of the portfolio covering all of it. A more complete plan subtracts the present value of expected Social Security income from the spending target before applying the 25× multiple.

How often should I recalculate my Coast FIRE number? Annually is a reasonable cadence for most people — often alongside a broader yearly financial check-in. Recalculating more frequently than that rarely changes the answer meaningfully, since the inputs (portfolio balance, spending target, years remaining) don't shift dramatically month to month, but a full year of either strong or weak market performance can meaningfully move where you actually stand relative to the target.

Does being self-employed or having variable income change the Coast FIRE math? Not the formula itself — it only cares about invested balance, years remaining, and assumed return, regardless of how the money was earned. What changes is the safety margin worth building in. Someone with volatile self-employment income has less certainty that they can cover a bad year of expenses without dipping into the coasted portfolio itself, which would undermine the "no more contributions needed" assumption the whole calculation rests on. A larger cash buffer outside the invested portfolio — six to twelve months of expenses rather than the standard three to six — is a reasonable adjustment for anyone coasting on irregular income.

Coast FIRE vs. Full FIRE: The Timeline Difference

Here's how the timelines typically compare for someone saving aggressively from age 25:

• Coast FIRE: Often achievable by age 30–35 for high earners saving 30–40% of income
• Barista FIRE / Lean FIRE: Often 5–10 years after Coast FIRE
• Full FIRE: Typically 15–25 years of aggressive saving from a zero base

The full Coast FIRE strategy guide explores the nuances of planning your coast phase, including how to verify your Coast FIRE status each year as return assumptions change.