What is Coast FIRE? The Complete Guide
Coast FIRE is the moment your portfolio is large enough that compound growth alone — with zero new contributions — will fund a traditional retirement. From that point, you only have to cover today's bills.
Key takeaways
- Coast FIRE means you can stop investing and still retire on time.
- It's reached by front-loading investments early in your career.
- Coast FIRE doesn't mean stopping work — it means stopping forced saving.
- Lower assumed returns mean a higher Coast FIRE number; be conservative.
- It's the most accessible FIRE milestone for average earners and a powerful career-flexibility tool.
What you'll learn
- Understand what Coast FIRE is and how it differs from standard FIRE
- Apply the Coast FIRE formula to your own age and target
- See how sensitive the number is to assumed real returns
- Recognise the career-flexibility upside of hitting Coast FIRE early
- Leave with an action plan to calculate and track your Coast FIRE number
Model Your Coast FIRE Number
Use the Coast FIRE Calculator to plug in your age, target, and expected real return — and see exactly how much you need invested today.
The Coast FIRE concept
Coast FIRE is reached when your invested net worth, left completely untouched, will compound into a full retirement portfolio by your traditional retirement age. From that point on, you only need to cover your current living expenses with current income. No more retirement contributions required.
The word "coast" is doing a lot of work here. You aren't retired. You aren't withdrawing from the portfolio. You're still earning a paycheck. But the heaviest lift of the FIRE journey — building the principal that compounds — is done. Time and the market do the rest.
Coast FIRE is the point at which your invested assets, with no further contributions, will grow into a full FIRE portfolio by your target retirement age.
How Coast FIRE differs from standard FIRE
- Standard FIRE: portfolio is big enough today to fund expenses today.
- Coast FIRE: portfolio is big enough today to become standard FIRE by age 65 (or whichever target age).
That difference is huge. The Coast FIRE number at age 35 can be roughly a quarter of the standard FIRE number — because compound growth has 30 years to do its work.
The Coast FIRE formula
The Coast FIRE number is the present value of your future FIRE target, discounted by your assumed real return:
Coast FIRE = (Annual Expenses × 25) ÷ (1 + r)n
Where r = expected real return and n = years until traditional retirement.
Example: A standard FIRE target of $1.25M at age 65, assuming a 5% real return:
- At age 25 (40 years to grow): about $177,500
- At age 30 (35 years to grow): about $226,500
- At age 35 (30 years to grow): about $289,500
- At age 40 (25 years to grow): about $369,300
- At age 45 (20 years to grow): about $471,400
- At age 50 (15 years to grow): about $601,200
- At age 55 (10 years to grow): about $767,300
The earlier you reach Coast FIRE, the smaller the number. Front-loading is the entire strategy.
How sensitive is the number to return assumptions?
Very. A 1% change in assumed return can move your Coast FIRE number by 25–40%, especially over long horizons. At age 35 targeting $1.25M:
- At 7% real: about $164,000
- At 5% real: about $289,000
- At 4% real: about $385,000
- At 3% real: about $514,000
Most planners use 4–5% real for projections. Model both ends of your range in the Coast FIRE Calculator — don't anchor on a single optimistic figure.
Why people aim for Coast FIRE
- It removes the pressure to keep maxing retirement accounts forever.
- It opens up career changes, lower-paid passion work, sabbaticals, or parental leave without derailing retirement.
- It's a realistic milestone for people who can't reach standard FIRE in 10 years.
- It buys real psychological freedom long before traditional retirement age.
- It pairs naturally with Barista FIRE if you want to drop to part-time work.
The career-flexibility multiplier
Coast FIRE is one of the highest-leverage moves in personal finance because of how it changes your job market. Once you no longer need to save for retirement, your minimum income requirement drops sharply. You can switch industries, start a business, take a research year, or work in a field that pays less but matters more to you.
Real-world examples
Example 1: The aggressive early saver
A 28-year-old developer maxes their 401(k) and IRA for six years, ending with $295,000 invested. Targeting a $1.25M standard FIRE number at 65 (5% real return), they cross Coast FIRE in their early 30s and shift to a smaller consultancy with better hours and a 25% pay cut.
Example 2: Coast FIRE through inheritance
A 40-year-old receives a $250,000 inheritance and invests it alongside an existing $150,000. With 25 years of compound growth, that's roughly $1.36M at 65, beating their $1.25M target. They've effectively hit Coast FIRE without the decade of front-loading.
Example 3: The mid-career pivot
A 45-year-old project manager has $480,000 invested. Their target is $1.4M at 65. With 20 years and a 5% real return, the portfolio grows to roughly $1.27M — just short. They add $5,000/year for the next five years to close the gap, then coast. Sanity-check this kind of projection with the Compound Growth Calculator.
Common mistakes
- Assuming an unrealistic return. Using a 7–8% real return makes your Coast FIRE number look reachable but fragile. Use 4–5% real for safety margin.
- Forgetting inflation. Always work in real (inflation-adjusted) numbers, not nominal ones.
- Touching the portfolio. Coast FIRE only works if you don't withdraw. A "small" $10k/year withdrawal breaks the compounding.
- Underestimating future expenses. Healthcare and housing in particular can move significantly over 25–35 years.
- Quitting work entirely. Coast FIRE means you still need to cover today's bills. If you stop working completely, you're attempting standard FIRE.
- Picking one age and freezing. Recalculate each year. Market drawdowns can push you back below Coast FIRE; bull markets can push you over.
Action steps
- Calculate your traditional FIRE number (annual expenses × 25).
- Pick a target retirement age and a conservative real return (4–5%).
- Use the Coast FIRE formula to find the present-value target at your current age.
- Compare your current invested assets to that target — note the gap or surplus.
- Build a savings plan to close the gap as quickly as your life allows.
- Once you cross Coast FIRE, redirect the freed-up savings rate to lifestyle, time, or a sabbatical fund — not to lifestyle inflation.
- Recheck the calculation each year and after any major market move.
Frequently asked questions
What's a typical Coast FIRE number?
Can I work part-time after reaching Coast FIRE?
What return rate should I use?
What if the market crashes after I hit Coast FIRE?
Is Coast FIRE the same as Barista FIRE?
Should I include my home equity in the calculation?
Can I reach Coast FIRE in my 20s?
Ready to Find Your Coast FIRE Number?
Plug in your age, target, and expected real return in the Coast FIRE Calculator — then keep exploring the FIRE variants.