How to Use This Coast FIRE Calculator
This calculator helps you determine your Coast FIRE number—the amount you need saved today so that compound growth alone will fund your retirement, without any additional contributions.
- Enter your current age and target retirement age. The gap between these determines your compounding period. More years = more growth = lower Coast FIRE number.
- Input your current retirement savings. Include 401(k), IRA, brokerage accounts—all investments earmarked for retirement.
- Set realistic return and inflation expectations. The default 7% return and 3% inflation gives roughly 4% real return—conservative but reasonable for a stock-heavy portfolio.
- Enter your desired retirement spending. Use today's dollars—the calculator adjusts for inflation. Be honest: underestimating means running out of money.
- Add your current annual contributions. This powers the comparison chart showing growth with vs. without continued saving.
The results show your Coast FIRE number, the age you'll reach it, and your Barista FIRE income (how much you'd need to earn if you stopped saving today). The chart visualizes both scenarios.
Understanding Coast FIRE Math
Coast FIRE leverages the power of compound growth. Once you have enough invested, time and returns do the heavy lifting—you just need to avoid touching the money until retirement.
The 4% Rule and Your Target
First, we calculate how much you need at retirement using the 4% rule: your annual spending × 25. Want to spend $50,000/year? You need $1,250,000. This assumes you can safely withdraw 4% annually, adjusted for inflation, without depleting your portfolio over 30 years.
Real vs. Nominal Returns
Nominal returns are what the market delivers (say, 7%). Real returns subtract inflation (7% - 3% ≈ 4%). We use real returns because your spending target is in today's dollars. A million dollars in 30 years won't buy what it buys today—real returns account for this.
The exact formula: Real Return = ((1 + Nominal) / (1 + Inflation)) - 1. With 7% returns and 3% inflation, that's ((1.07) / (1.03)) - 1 = 3.88% real return.
Working Backward: Your Coast FIRE Number
Coast FIRE Number = Target Nest Egg ÷ (1 + Real Return)^Years
Example: Need $1,250,000 in 30 years at 4% real return. Coast FIRE Number = $1,250,000 ÷ (1.04)^30 = $385,000. If you have $385,000 today and never add another dollar, it'll grow to $1,250,000 (in today's purchasing power) by retirement.
The Power of Time
A 25-year-old has 40 years of compounding; their Coast FIRE number is much lower than a 45-year-old with 20 years. This is why early saving is so powerful—and why Coast FIRE is achievable younger than you might think.
Examples
Example 1: 25-Year-Old with $50,000 Saved
Jamie is 25, has $50,000 in retirement accounts, wants to spend $40,000/year in retirement at age 65.
- Nest egg needed: $40,000 × 25 = $1,000,000
- Years to retirement: 40 years
- Real return: 4% (7% nominal - 3% inflation)
- Coast FIRE number: $1,000,000 ÷ (1.04)^40 = $208,289
- Progress: 24% there ($50K / $208K)
- Coast FIRE age: approximately 38 (if continuing to save $10K/year)
Jamie needs to accumulate $158,000 more to coast. With aggressive saving, they could reach Coast FIRE by their late 30s.
Example 2: 35-Year-Old with $200,000 Saved
Alex is 35, has $200,000 saved, wants $60,000/year spending, planning to retire at 60.
- Nest egg needed: $60,000 × 25 = $1,500,000
- Years to retirement: 25 years
- Real return: 4%
- Coast FIRE number: $1,500,000 ÷ (1.04)^25 = $562,500
- Progress: 36% ($200K / $562K)
- Coast FIRE age: approximately 42
Alex is 7 years from Coast FIRE. Continuing current contributions, they'll hit the number around age 42 and could then reduce work to cover only current expenses.
Example 3: 40-Year-Old with $400,000 Saved
Morgan is 40, has $400,000, wants $50,000/year spending, targeting traditional retirement at 65.
- Nest egg needed: $50,000 × 25 = $1,250,000
- Years to retirement: 25 years
- Real return: 4%
- Coast FIRE number: $1,250,000 ÷ (1.04)^25 = $468,750
- Progress: 85% ($400K / $469K)
- Coast FIRE age: 42
Morgan is almost there! In about 2 years, they'll hit Coast FIRE and can shift to lower-stress work that just covers current expenses.
Frequently Asked Questions
What is Coast FIRE?
Coast FIRE (Financial Independence, Retire Early) is the point where you've saved enough that compound growth alone will fund your retirement—without any additional contributions. Once you reach your Coast FIRE number, you can "coast" by working just enough to cover current expenses, letting your investments grow on autopilot until retirement age.
What is Barista FIRE?
Barista FIRE is a variation where you have enough saved to partially fund retirement but still need some income. The name comes from the idea of working a low-stress job (like a barista) that provides health insurance and covers basic expenses while your investments grow. It's the bridge between Coast FIRE and full FIRE.
What is the 4% rule?
The 4% rule is a retirement guideline stating you can withdraw 4% of your portfolio in year one of retirement, then adjust for inflation each year, with low risk of running out of money over 30 years. It's based on the Trinity Study. To use it: multiply your annual spending by 25 to get your target nest egg. Example: $40,000/year spending × 25 = $1,000,000 needed.
How much do I need to retire?
Using the 4% rule: multiply your desired annual spending by 25. For $50,000/year, you need $1.25 million. For $80,000/year, you need $2 million. This assumes a 30-year retirement. If retiring earlier or wanting extra safety margin, multiply by 28-33 instead (3-3.5% withdrawal rate).
What return should I assume?
A 7% nominal return is a reasonable long-term assumption for a stock-heavy portfolio, based on historical S&P 500 returns. More conservative investors might use 6%. The key is accounting for inflation (typically 2-3%), giving a real return of 4-5%. This calculator uses real returns to show purchasing power.
Does Coast FIRE account for inflation?
Yes, this calculator uses real (inflation-adjusted) returns. When you enter 7% return and 3% inflation, the calculator uses approximately 3.9% real return. Your spending target is in today's dollars, and the growth projections maintain purchasing power. This gives you an accurate picture of future needs.
Can I Coast FIRE in my 30s?
Absolutely. It's actually easier when you're younger because you have more compounding time. A 30-year-old with $200,000 saved and 35 years until retirement has much more growth potential than a 50-year-old with the same amount and only 15 years. The earlier you reach Coast FIRE, the more flexibility you have in your career.
Financial Disclaimer
This calculator provides estimates for informational purposes only and does not constitute financial, tax, or investment advice. Tax laws vary by jurisdiction and change frequently. Results are based on simplified models and may not reflect your specific situation. Always consult a qualified tax professional, CPA, or financial advisor before making financial decisions. ToolVamp is not liable for any actions taken based on these calculations.