Coast FIRE Calculator

What Is Coast FIRE?

Coast FIRE is the point where your existing savings, left to grow untouched, will reach your full FIRE number by traditional retirement age through investment returns alone - no additional contributions needed. Enter your annual expenses, current savings, and expected return rate in the calculator above. The Coast FIRE number tells you how much you need saved right now so that compounding does the remaining work. Once you reach it, you only need to earn enough to cover current expenses, not save for retirement, dramatically reducing the income pressure and opening the door to lower-stress or part-time work.

Coast FIRE vs Traditional FIRE

Traditional FIRE requires accumulating the full target before leaving full-time work. Coast FIRE identifies a much lower intermediate milestone. FIRE number at $50,000/year expenses: $1,250,000. Coast FIRE number for a 35-year-old (30 years to age 65, 7% return): $1,250,000 / (1.07)^30 = $164,200. Reaching $164,200 at age 35 means you never need to save another dollar for retirement - the portfolio grows to $1,250,000 by 65 through compounding alone. The difference between needing $1,250,000 and needing $164,200 is the difference between working intensely for another 15 years versus shifting to coast mode now.

Coast FIRE Numbers by Age

Assuming a $1,250,000 FIRE target and 7% real return: Coast FIRE at age 25 (40 years to grow): $83,500. At 30: $117,200. At 35: $164,200. At 40: $230,300. At 45: $323,000. At 50: $453,000. The younger you are, the less you need because time gives compounding more room to work. A 25-year-old who saves aggressively for just 5-7 years to accumulate $83,500 can coast the remaining 40 years knowing their retirement is mathematically secured. This realization motivates many young professionals to front-load their saving during early career years when expenses are typically lower.

Life After Reaching Coast FIRE

Once your portfolio exceeds the Coast FIRE threshold, your income only needs to cover current living expenses. This unlocks options: switch to a less demanding job that pays less but offers better work-life balance. Go part-time and spend afternoons with your children. Pursue passion projects, freelance work, or creative endeavors that might not pay enough to fund both living expenses and retirement savings. Start a business with less financial pressure because your retirement nest egg is already working independently. The psychological shift from "I must earn enough to live AND save" to "I only need to cover today" is transformative for career and lifestyle decisions.

The Risk of Relying on Projected Returns

Coast FIRE assumes a specific annual return over decades. At 7%: a $165,000 portfolio reaches $1,255,000 in 30 years. At 5%: only $713,000. At 9%: $2,191,000. The actual return over your specific 30-year window is unknowable in advance. Mitigating this uncertainty: use a conservative return assumption (5-6% real rather than 7%), continue making modest contributions even after reaching Coast FIRE (an extra $200/month provides significant insurance), and maintain a flexible withdrawal rate in retirement. Coasting with a small safety margin built in prevents the catastrophic scenario where poor market returns during your specific decades leave the portfolio short.

Combining Coast FIRE with Part-Time Work

A household at Coast FIRE needing $50,000/year to cover current expenses: one partner working full-time at $55,000 covers expenses with $5,000 surplus. Both partners working part-time (20 hours each at $18/hour) earn approximately $37,440 combined, requiring only $12,560 from savings or side income. A single person at Coast FIRE earning $30/hour needs only 32 hours/week to cover $50,000 in annual expenses. Each of these scenarios represents dramatically more freedom than the standard 40-50 hour workweek driven by the need to simultaneously fund both living expenses and retirement savings. The math shifts once the retirement funding requirement disappears.

Calculating Your Personal Coast FIRE Target

Step 1: Determine your FIRE number (annual expenses x 25). Step 2: Choose your target retirement age (55, 60, or 65). Step 3: Calculate years until target age. Step 4: Divide FIRE number by (1 + expected return)^years. A 32-year-old spending $45,000/year targeting age 60: FIRE number = $1,125,000. Years to 60 = 28. At 7%: $1,125,000 / (1.07)^28 = $166,900. At 6%: $215,100. At 5%: $278,600. Using the conservative 5-6% assumption and aiming for the higher end provides a safety margin against underperformance. Once your portfolio passes this number, you have reached Coast FIRE for your specific parameters.

Coast FIRE and the Barista FIRE Overlap

Barista FIRE specifically involves working a part-time job (like a barista at Starbucks) that provides health insurance benefits while the portfolio compounds. Starbucks offers health coverage to employees working 20+ hours/week, solving the biggest non-investment expense in early semi-retirement. Other companies with part-time health benefits: Costco, UPS, REI, Chipotle, and Trader Joe. The Coast FIRE portfolio handles retirement math while the part-time job covers current expenses and health insurance. This combination addresses the two biggest objections to leaving traditional employment: retirement security and healthcare coverage, without requiring the full FIRE number to be accumulated first.

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