Coast FIRE is the point where you have invested enough money that — even if you never save another cent — your portfolio will grow to support retirement by a target age. Once you hit Coast FIRE, you only need to earn enough to cover current expenses. No more aggressive saving required. This guide explains the math, walks through realistic examples, and shows how to figure out whether you’re closer to Coast FIRE than you think.
What Is Coast FIRE?
Traditional FIRE (Financial Independence, Retire Early) means accumulating enough wealth to cover expenses indefinitely, usually using the 4% withdrawal rule. Many people find the aggressive savings rates required — often 50% or more — difficult to sustain for years.
Coast FIRE offers a psychological and practical milestone along the way. The idea is simple: compound interest does the heavy lifting once you have a sufficient base invested. If a 28-year-old has $150,000 invested and plans to retire at 60, that money could grow to over $1,000,000 on its own at a 6% real return — without any additional contributions.
At that point, the person has “coasted.” They still work and earn income, but they no longer need to save for retirement. Every dollar earned can go toward current living expenses. Many people find this liberating because it opens doors to lower-stress jobs, part-time work, career changes, or creative pursuits without jeopardizing their future.
Coast FIRE vs. Other FIRE Variants
| FIRE Variant | Definition |
|---|---|
| Traditional FIRE | Portfolio covers all expenses via passive income — stop working entirely |
| Coast FIRE | Portfolio will grow to your FI number on its own — stop saving, keep earning |
| Barista FIRE | Semi-retired with part-time income covering remaining expenses |
| Lean FIRE | Full FIRE but with minimal expenses (often under $40,000/year) |
| Fat FIRE | Full FIRE with higher spending (often $100,000+/year) |
Coast FIRE is not full financial independence. It is a milestone that removes the pressure to save aggressively while compound growth handles the rest. For a deeper explanation of the FIRE spectrum, see our guide on what financial independence actually means.
The Coast FIRE Formula
The Coast FIRE calculation answers one question: “How much do I need invested today so that compound growth alone reaches my FI number by my target retirement age?”
The formula works backward from the future value:
Coast FIRE Number = FI Number / (1 + r)^n
Where:
- FI Number = Annual expenses in retirement x 25 (based on the 4% rule)
- r = Expected real (inflation-adjusted) annual return
- n = Years until target retirement age
Breaking Down Each Variable
FI Number: This is the total portfolio value needed to retire. If expected annual expenses in retirement are $50,000, the FI number is $50,000 x 25 = $1,250,000. For a detailed walkthrough of this calculation, see how to calculate your FI number.
Real return (r): Most Coast FIRE calculations use a 5%–7% real return for a diversified stock portfolio. “Real” means after adjusting for inflation — so the calculation automatically accounts for rising costs over time. A 6% real return is a commonly used middle estimate.
Years to retirement (n): The gap between your current age and the age at which you plan to start withdrawing. A larger gap means more compounding time, which dramatically lowers the Coast FIRE number.
Coast FIRE Calculation Examples
Example 1: Age 25, Retiring at 60
- Expected annual expenses in retirement: $50,000
- FI Number: $50,000 x 25 = $1,250,000
- Real return: 6%
- Years to retirement: 35
Coast FIRE Number = $1,250,000 / (1.06)^35 = $162,500
If a 25-year-old has $162,500 invested today, they could theoretically stop saving entirely and still have roughly $1,250,000 by age 60 — enough to withdraw $50,000 per year using the 4% rule.
Example 2: Age 30, Retiring at 55
- Expected annual expenses: $60,000
- FI Number: $60,000 x 25 = $1,500,000
- Real return: 6%
- Years to retirement: 25
Coast FIRE Number = $1,500,000 / (1.06)^25 = $349,400
Shorter time horizon and higher expenses mean a significantly larger amount is needed to coast.
Example 3: Age 35, Retiring at 65
- Expected annual expenses: $45,000
- FI Number: $45,000 x 25 = $1,125,000
- Real return: 6%
- Years to retirement: 30
Coast FIRE Number = $1,125,000 / (1.06)^30 = $195,700
Despite being older, the 30-year runway and moderate expenses keep this number accessible.
Coast FIRE Numbers at a Glance
The following table shows Coast FIRE numbers for a $1,000,000 FI target at 6% real return:
| Current Age | Retire at 55 | Retire at 60 | Retire at 65 |
|---|---|---|---|
| 25 | $174,100 | $130,000 | $97,000 |
| 30 | $233,000 | $174,100 | $130,000 |
| 35 | $311,800 | $233,000 | $174,100 |
| 40 | $417,300 | $311,800 | $233,000 |
| 45 | $558,400 | $417,300 | $311,800 |
The power of time is obvious: a 25-year-old needs less than $100,000 to coast toward a $1,000,000 retirement portfolio at age 65. A 45-year-old targeting the same amount at age 55 needs over $558,000.
How Assumed Return Rate Changes Everything
The real return assumption is the most sensitive variable in the Coast FIRE formula. Small changes in the assumed return produce large differences in the result because of how compounding works over decades.
For a $1,250,000 FI number with 30 years to retirement:
| Real Return | Coast FIRE Number |
|---|---|
| 4% | $385,400 |
| 5% | $289,000 |
| 6% | $217,300 |
| 7% | $164,100 |
| 8% | $124,300 |
The gap between 5% and 7% is $124,900 — a meaningful difference. Some people prefer to use a conservative 5% real return to build in a margin of safety, while others use the historical average of roughly 7% for a globally diversified equity portfolio.
One approach many people take is to calculate their Coast FIRE number at two or three different return assumptions. If you’ve hit the number at the conservative end, you can feel more confident about easing off on savings.
What Happens After You Reach Coast FIRE?
Reaching Coast FIRE does not mean retirement. It means one thing: active saving for retirement becomes optional. You still need income to cover current living expenses, taxes, and any non-retirement financial goals.
Common Post-Coast FIRE Strategies
Downshift to lower-paying, more fulfilling work. Many people find that removing the need to maximize income opens career paths that previously felt financially irresponsible — teaching, nonprofit work, freelancing, or creative work.
Reduce hours. Some people keep their current role but move to part-time, negotiate reduced schedules, or take extended breaks between contracts.
Redirect savings toward other goals. Money that previously went to retirement investments can be redirected to education, travel, housing, charitable giving, or starting a business.
Keep saving anyway. Some people hit Coast FIRE and decide to keep saving because the habits are established and the extra cushion provides peace of mind. The key difference is that continued saving becomes a choice, not a requirement.
The Psychological Benefit
One often-overlooked benefit of Coast FIRE is the reduction in financial anxiety. Knowing that retirement is mathematically handled — even if you never save another dollar — can reduce stress around job changes, economic downturns, or unexpected expenses. It shifts the mindset from “I must save” to “I choose to save.”
Limitations and Risks of Coast FIRE
Coast FIRE relies on several assumptions that may not hold over decades. It is important to understand these limitations rather than treating the calculation as a guarantee.
Market Returns Are Not Guaranteed
Historical stock market returns average around 7% real (after inflation) over long periods, but decade-long stretches of below-average returns do occur. The “lost decade” of 2000–2009 saw near-zero real returns for U.S. stocks. Someone who hit their Coast FIRE number in 2000 and stopped saving would have been behind schedule a decade later.
Inflation May Outpace Assumptions
Using real returns helps adjust for inflation, but future inflation rates are uncertain. If your expenses rise faster than general inflation — healthcare costs, for example — the FI number you calculated today might not be sufficient.
Life Circumstances Change
Expenses rarely stay constant over 20–30 years. Marriage, children, housing changes, health events, or geographic moves can all shift spending patterns. A Coast FIRE number calculated at age 25 might need revisiting at age 35.
Sequence of Returns Risk in Early Years
If a major market downturn happens shortly after you stop contributing, the recovery path is harder without new contributions to buy shares at lower prices. Dollar-cost averaging provides a natural cushion during volatile markets — one you lose when you stop investing.
Mitigation Strategies
Many people address these risks by:
- Using conservative return assumptions (5% instead of 7%)
- Adding a 10–20% buffer to their Coast FIRE number
- Continuing to save at a reduced rate rather than stopping entirely
- Recalculating periodically as circumstances change
- Maintaining an emergency fund outside retirement investments
How to Track Progress Toward Coast FIRE
Tracking progress toward Coast FIRE requires knowing two things: your current invested balance and your Coast FIRE target number.
Step 1: Determine Your FI Number
Estimate annual expenses in retirement and multiply by 25. Be realistic about what “retirement expenses” look like. Some costs decrease (commuting, work clothes), while others may increase (healthcare, travel).
Step 2: Calculate Your Coast FIRE Number
Use the formula with your chosen return rate and years until retirement. Consider calculating at both a conservative and moderate return assumption.
Step 3: Track Your Invested Assets
Only count invested assets — money in retirement accounts (401k, IRA, pension equivalents), taxable brokerage accounts, and other long-term investments. Do not count your emergency fund, home equity (unless you plan to sell), or money earmarked for near-term goals.
Step 4: Monitor the Gap
Your Coast FIRE gap is simply:
Gap = Coast FIRE Number − Current Invested Assets
As your investments grow through both contributions and market returns, this gap narrows. Tracking it monthly or quarterly provides a clear picture of progress.
A personal finance app like Monavio can help by aggregating investment balances alongside everyday spending — giving a unified view of both your net worth trajectory and your expense baseline for FI calculations. Try Monavio free for 14 days to see how close you are to your Coast FIRE milestone.
Coast FIRE vs. Full FIRE: Which to Target?
There is no universally correct answer. The right target depends on individual values, career satisfaction, and risk tolerance.
Consider targeting Coast FIRE first if:
- You enjoy your work but want to remove the financial pressure
- You are in your 20s or early 30s and have decades of compounding ahead
- You want a psychologically meaningful milestone while continuing to work
- You want the option to switch careers without worrying about retirement
Consider targeting full FIRE if:
- You want to stop working entirely or make work fully optional
- You are closer to your target retirement age and need a larger portfolio now
- Your current spending is well-established and unlikely to change dramatically
Many people find that Coast FIRE serves as a powerful intermediate target. Hitting it often provides the confidence and motivation to continue toward full financial independence.
Using the FIRE Calculator for Coast FIRE
Our FIRE calculator guide covers the broader FIRE math, including how savings rate drives the overall timeline. Coast FIRE is one milestone along that journey. By understanding both the full FIRE timeline and the Coast FIRE crossover point, you can set goals that match your lifestyle — whether that means aggressive saving in your 20s and coasting by 35, or a steady pace toward full independence by 50.
Frequently Asked Questions
Is Coast FIRE realistic for someone starting in their 30s?
Yes. A 30-year-old with a $1,000,000 FI target and a 35-year timeline to age 65 would need roughly $130,000 invested to coast at a 6% real return. Many people find this achievable, especially with employer-matched retirement contributions. The key variable is time — even starting at 35, a 30-year runway provides significant compounding potential.
What if the market crashes right after I hit Coast FIRE?
This is the most common concern. One approach is to add a buffer of 10–20% above the calculated Coast FIRE number before reducing savings. Another strategy is to “slow coast” — reducing savings rate significantly rather than stopping entirely. This maintains some dollar-cost averaging while still capturing most of the lifestyle benefits. Periodic recalculation (annually or after major market moves) helps catch any shortfall early.
Should I include my home equity in the Coast FIRE calculation?
Generally, no — unless you specifically plan to downsize or sell and invest the proceeds. Coast FIRE is about invested assets that compound and generate returns. A primary residence typically does not produce income during the accumulation phase. Including it overstates how much money is actually working for you in the market.
This article is for educational purposes only and does not constitute financial advice. Investment returns are not guaranteed, and past performance does not predict future results. Consider consulting a qualified financial advisor for decisions specific to your situation.