Of all the milestones in the FIRE (Financial Independence, Retire Early) movement, Coast FIRE may be the most underrated. It is less dramatic than full financial independence, but for many people it is more practical, more achievable, and just as life-changing. Reaching Coast FIRE means you have crossed a threshold where your investments, left alone, will grow into enough to fund a traditional retirement — and you never need to save another dollar for retirement again.
What Is Coast FIRE?
Coast FIRE is the point at which your current investment portfolio is large enough that, given a realistic rate of growth, it will compound into your full retirement target by the age you plan to retire — without any additional contributions.
You still need to work to cover your living expenses. But the pressure to save for the future disappears. The money you previously directed into retirement accounts becomes available for anything else: paying off a mortgage faster, starting a business, traveling, supporting family, or simply living on less income.
How It Differs From Full FIRE
Full financial independence means your portfolio is already large enough to fund your lifestyle indefinitely — typically 25× your annual expenses (see the 4% Rule and our FIRE Calculator). At full FIRE, you can stop working entirely.
Coast FIRE is earlier and easier to reach. You still work, but the retirement savings portion of your financial plan is complete. You have "coasted" past the need to keep funding the future.
| Milestone | Portfolio size | Do you still work? | Do you still save for retirement? |
|---|---|---|---|
| Debt-free + emergency fund | $0+ | Yes | Yes |
| Coast FIRE | Grows to target on its own | Yes | No |
| Full FIRE | 25× annual expenses | Optional | No |
How to Calculate Your Coast FIRE Number
Coast FIRE is not a single dollar amount — it is a relationship between your current portfolio, your target retirement portfolio, your expected return, and the time remaining.
Step 1: Set Your Retirement Target
Estimate the portfolio you need at retirement. A common method is to multiply your expected annual retirement expenses by 25 (the 4% rule). For example, if you plan to spend $40,000/year in retirement, your target is $1,000,000.
Step 2: Choose a Real-Expected Return
Use a real return (after inflation) of roughly 6–7% for a diversified stock-heavy portfolio. Using a real return means your final number is already in today's purchasing power, so you do not need to adjust the target for inflation separately.
Step 3: Calculate How Much You Need Today
The formula: Current portfolio needed = Target ÷ (1 + r)^(years remaining)
Where r is your expected real annual return and years remaining is the time until retirement.
Example: target $1,000,000, real return 6.5%, 30 years to retirement. $1,000,000 ÷ (1.065)^30 = $1,000,000 ÷ 6.61 ≈ $151,000
If you have $151,000 invested today and 30 years until retirement, you have reached Coast FIRE. At 6.5% real growth, that $151,000 becomes roughly $1,000,000 in 30 years with no further contributions.
Use the Compound Interest Calculator or Investment Growth Calculator to model your own numbers precisely.
Step 4: Compare to Your Current Portfolio
If your current portfolio equals or exceeds the Coast FIRE threshold, you have arrived. If not, the gap tells you how much more you need to invest before you can coast.
Why Coast FIRE Is So Powerful Early
Because of compound growth, the earlier you reach Coast FIRE, the smaller the required portfolio. Compare the Coast FIRE threshold for a $1,000,000 target at 6.5% real returns:
| Years to retirement | Coast FIRE portfolio needed |
|---|---|
| 40 | $92,000 |
| 30 | $151,000 |
| 20 | $284,000 |
| 10 | $533,000 |
| 5 | $747,000 |
A 25-year-old with 40 years until retirement needs only about $92,000 invested to coast. A 55-year-old with 10 years needs $533,000. Time is the single most valuable asset in reaching Coast FIRE — which is exactly why starting to invest early matters so much. See our Simple vs Compound Interest guide for the underlying math.
What to Do Once You Reach Coast FIRE
Reaching Coast FIRE is not a signal to stop contributing if you enjoy your work and want to retire earlier than your planned age. It is a signal that your minimum viable retirement plan is funded. Your options expand:
- Keep saving to reach full FIRE sooner. Every additional dollar invested accelerates your timeline. Use the FIRE Calculator to see how extra contributions change your independence date.
- Redirect income elsewhere. Pay off your mortgage, fund a child's education, or take a lower-stress job that simply covers living expenses.
- Take more career risk. With retirement already on track, you can start a business or change careers without risking your retirement.
- Reduce financial stress. Even if you keep saving, knowing the floor is secured changes how you experience work and money decisions.
Common Coast FIRE Mistakes
Using nominal returns instead of real returns. If you assume 10% nominal growth but inflation is 3%, your purchasing power target should be inflated too. Using real returns (about 6.5%) for both sides keeps the comparison honest and avoids a false sense of security.
Forgetting that you still must cover living expenses. Coast FIRE funds your future retirement. Until you reach full FIRE, you still need income for rent, food, and daily life.
Assuming constant returns. Markets do not return 6.5% every year. Sequence-of-returns risk still applies, especially if you are close to retirement. Build a margin of safety.
Counting money you cannot access. Money locked in a 401(k) or traditional IRA grows toward Coast FIRE, but early access has restrictions. Coast FIRE calculations can include retirement accounts, but understand the withdrawal rules for each account type. See 401(k) vs IRA for the differences.
A Realistic Example
Maya is 30 and wants to retire at 60 with $1,000,000 (in today's dollars). She has $90,000 invested in a Roth IRA and a 401(k). At 6.5% real return over 30 years, she needs roughly $151,000 to coast. She is about $61,000 short.
If she invests $700/month at the same 6.5% real return, she reaches the $151,000 Coast FIRE threshold in about 5 years. After that, even if she never contributes another dollar, the portfolio grows to roughly $1,000,000 by age 60. In practice, Maya keeps investing and reaches full FIRE far earlier than 60.
The Retirement Savings Calculator models exactly this kind of projection.
Frequently Asked Questions
Q: Does Coast FIRE count money in my 401(k)? Yes. All invested assets that will grow toward retirement count — 401(k), IRA, Roth, and taxable brokerage. Just be aware of withdrawal restrictions and tax treatment for each account. Your retirement accounts all compound toward Coast FIRE.
Q: What return rate should I use for Coast FIRE? A real (inflation-adjusted) return of 6–7% is reasonable for a stock-heavy, diversified portfolio. Using a real return means your target stays in today's dollars. Be conservative — underestimating returns is far safer than overestimating them.
Q: Can I really stop saving for retirement at Coast FIRE? Mathematically, yes — your investments will reach your target on their own. Practically, most people keep saving to retire earlier or build a larger safety margin. Coast FIRE is freedom of choice, not a requirement to stop.
Q: Is Coast FIRE realistic on an average salary? Yes, especially if you start early. Because compound growth does most of the work over long time horizons, consistent modest investing in your 20s can reach Coast FIRE well before age 40. The Rule of 72 shows why starting early matters so much.
Q: What is the difference between Coast FIRE and Barista FIRE? Coast FIRE means your retirement is funded and you work only to cover living expenses. Barista FIRE means you have a partial portfolio and work part-time (sometimes with employer benefits) to cover the gap. They overlap but are not identical.