Coast FIRE is the point where your current savings, left to grow through compound interest alone, will reach your full Financial Independence number by retirement age — meaning you can stop saving and only earn enough to cover today’s expenses.
Unlike traditional FIRE (Financial Independence, Retire Early), which requires aggressive saving until you can live entirely off investments, Coast FIRE gives you a milestone where the pressure to save disappears. Once you cross the Coast FIRE threshold, time and compound interest do the heavy lifting for you.
How Coast FIRE Works
The Coast FIRE formula is straightforward. You need to determine the future value of your current investments, assuming a reasonable rate of return, and check whether that future value meets your retirement target.
The formula:
Coast FIRE Number = FI Target / (1 + r)^n
Where:
- FI Target is your desired portfolio at retirement (often 25x your annual expenses, per the 4% rule)
- r is your expected annual real rate of return (typically 5-7% after inflation)
- n is the number of years until your target retirement age
Concrete example: Suppose you are 30 years old, have $100,000 saved, expect a 7% annual return, and want $1,000,000 by age 60.
Your Coast FIRE number = $1,000,000 / (1.07)^30 = $1,000,000 / 7.612 = $131,367
Since you have $100,000 saved, you are not quite at Coast FIRE yet. You need roughly $31,000 more. But once you reach $131,367, you could theoretically stop contributing to retirement accounts entirely. At 7% annual growth, that amount grows to $1,000,000 by the time you turn 60.
If your annual expenses are $40,000 in retirement, the 4% rule says you need $1,000,000. So $131,367 at age 30 is your Coast FIRE number.
Calculate Your Coast FIRE Number
Use the interactive calculator below to find your personal Coast FIRE number. Adjust your current age, savings, expected returns, and retirement target to see exactly where you stand.
Coast FIRE Calculator
Calculate how much you need saved today to coast to Financial Independence without additional contributions
Savings rate: 40.0%
Coast FIRE vs Other FIRE Types
Coast FIRE is one of several FIRE variations, each suited to different lifestyles and risk tolerances:
| FIRE Type | Annual Spending | Portfolio Needed (4% Rule) | Key Idea |
|---|---|---|---|
| Lean FIRE | $25,000-$40,000 | $625K-$1M | Minimalist lifestyle, lower target |
| Coast FIRE | Varies | Current savings grow to target | Stop saving, just cover expenses |
| Barista FIRE | $40,000-$60,000 | Partial portfolio + part-time income | Semi-retirement with some work |
| Regular FIRE | $40,000-$60,000 | $1M-$1.5M | Full financial independence |
| Fat FIRE | $100,000+ | $2.5M+ | Maintain a premium lifestyle |
Lean FIRE is for minimalists who can thrive on $25,000-$40,000 per year. You can calculate your Lean FIRE number to see how a frugal lifestyle changes your timeline.
Barista FIRE means you have enough invested that part-time work covers the gap. Try the Barista FIRE calculator to find your number.
Fat FIRE targets a luxurious post-retirement lifestyle. The Fat FIRE calculator shows what it takes to maintain $100K+ in annual spending.
Coast FIRE is unique because it is not about a specific spending level — it is about reaching a savings threshold after which compound growth handles everything. It is the most psychologically freeing milestone because it removes the pressure of constant saving.
Coast FIRE for Digital Nomads
If you are a digital nomad or remote worker, geo-arbitrage can dramatically accelerate your path to Coast FIRE.
Geo-arbitrage means earning in a strong currency (USD, EUR, GBP) while living in a lower-cost country. This strategy can double or triple your savings rate during the accumulation phase, helping you hit your Coast FIRE number years earlier.
Consider this scenario:
- Living in San Francisco: $4,000/month expenses, saving $2,000/month on a $6,000 income
- Living in Chiang Mai, Thailand: $1,500/month expenses, saving $4,500/month on the same $6,000 income
At the higher savings rate, you reach your Coast FIRE number in roughly half the time. And once you have hit Coast FIRE, the reduced cost of living in a geo-arbitrage location means you need even less income during the coasting phase.
Use the geo-arbitrage tool to compare cities and see how location independence affects your FI timeline. IndepAI is the only tool that combines FIRE planning with location-independent lifestyle optimization, showing you exactly how moving to a different city changes your path to financial freedom.
Common Coast FIRE Mistakes
1. Ignoring Inflation
A 7% nominal return is not a 7% real return. If inflation averages 3%, your real return is closer to 4%. Always use real (inflation-adjusted) returns in your Coast FIRE calculation, or adjust your target upward for future inflation. Underestimating inflation is the most common reason people fall short of their Coast FIRE targets.
2. Assuming Constant Returns
Markets do not return a steady 7% per year. Some years you gain 25%, others you lose 20%. Sequence-of-returns risk is real: a major downturn early in your coasting period can permanently reduce your portfolio’s growth trajectory. Build in a 10-20% margin of safety above your calculated Coast FIRE number.
3. Not Accounting for Healthcare
If you plan to coast in your 30s or 40s, you may face decades without employer-sponsored health insurance. In the US, marketplace plans can cost $400-$800/month for an individual. Factor this into your “coasting expenses” — it is a significant line item that many Coast FIRE calculators ignore.
4. Forgetting About Lifestyle Inflation
Your expenses at 30 may look very different from your expenses at 50. Marriage, children, aging parents, and changing health needs can all increase spending. Periodically re-evaluate your Coast FIRE number as your life circumstances evolve.
5. Neglecting Tax-Advantaged Accounts
Even after reaching Coast FIRE, it may still make sense to contribute to tax-advantaged accounts (401k match, Roth IRA) if you are earning income. The tax benefits compound over time and provide additional security. Coast FIRE does not mean you should stop all financial optimization — just that you no longer need to save at a high rate.
Frequently Asked Questions
How much money do I need for Coast FIRE?
Your Coast FIRE number depends on your age, target retirement age, expected investment returns, and desired retirement spending. For example, a 30-year-old targeting $1M at age 60 with 7% returns needs roughly $131,000 saved today. Use our Coast FIRE calculator above to find your exact number.
What is the difference between Coast FIRE and regular FIRE?
Regular FIRE requires you to save and invest aggressively until your portfolio covers all living expenses indefinitely. Coast FIRE is the point where your existing savings will grow to your full FIRE number through compound interest alone, meaning you only need to earn enough to cover current expenses without saving anything additional.
Can I achieve Coast FIRE faster with geo-arbitrage?
Yes. Geo-arbitrage dramatically accelerates Coast FIRE by reducing your current living expenses. If you earn in USD or EUR while living in a lower-cost country, you can save more aggressively in the early years, reaching your Coast FIRE number sooner. Once you hit Coast FIRE, your reduced expenses also mean you need less income during the coasting phase.
What rate of return should I assume for Coast FIRE calculations?
Most financial planners use 7% nominal return (roughly 10% market return minus 3% inflation) for long-term stock market investments. Conservative planners may use 5-6%. The key is to be consistent and realistic — overly optimistic assumptions can lead to a false sense of security.
Is Coast FIRE safe? What are the risks?
Coast FIRE carries risks including sequence-of-returns risk (poor market performance early on), inflation exceeding expectations, and unexpected expenses like healthcare. It is important to build in a margin of safety, maintain an emergency fund, and periodically re-evaluate your Coast FIRE number as circumstances change.
Related Tools
Ready to plan your path to Coast FIRE? These tools can help:
- Coast FIRE Calculator — Calculate your exact Coast FIRE number with personalized inputs
- FI Calculator — See your full Financial Independence timeline and milestone tracking
- Geo-Arbitrage Tool — Compare cities worldwide and see how location affects your FI date
