Calculate when you reach Coast FIRE - the point where you can stop saving for retirement and let compound interest do the work. Determine your Coast FI number based on target retirement age, current savings, and expected returns. Essential tool for semi-retirement planning, downshifting careers, or reducing work hours while maintaining retirement security. Compare Coast FIRE vs Traditional FIRE timelines. Includes 2025 calculations for ages 30-50 with various retirement targets from age 55-70.
Frequently Asked Questions
What is Coast FIRE and how does it work in 2025?
Coast FIRE (Coast Financial Independence Retire Early) is achieving enough retirement savings that you never need to contribute another dollar - your existing balance will compound to your retirement goal through investment growth alone.
Unlike traditional FIRE requiring 25x annual expenses immediately, Coast FI lets you stop aggressive saving years earlier while maintaining full retirement security.
How It Works: Calculate retirement goal ($1.5M at age 65 for $60k/year expenses).
Determine years until retirement (age 35 → 30 years).
Apply compound interest backward to find Coast FI number today.
Real Example - Age 35 Planning for Age 65 Retirement: Retirement goal $1.5M in 30 years.
Assuming 7% annual returns: Coast FI number = $1,500,000 ÷ (1.07)^30 = $196,730.
Meaning: If you have $196,730 saved at age 35, stop contributing entirely.
By age 65, natural growth reaches $1,500,000 (without any additional savings).
Your money works while you live life.
Key Differences vs Traditional FIRE: Traditional FIRE needs 25x expenses now ($1.5M at age 35 to retire immediately).
Coast FI needs only $196,730 at age 35 (13% of traditional FIRE amount).
You continue working but without retirement savings pressure - cover living expenses only.
Benefits of Reaching Coast FIRE: Stop aggressive 50-70% savings rate, reduce to 0-10%.
Switch to lower-stress or passion-driven career (accept 30-50% pay cut safely).
Work part-time (20-30 hours/week instead of 40-60).
Take career sabbatical or extended travel (1-2 years off).
Pursue entrepreneurship without retirement account worries.
Real Coast FI Example - Software Engineer Age 30: Current savings $150k, Living expenses $50k/year, Current salary $120k (saving $70k/year aggressively).
Coast FI Analysis: Retirement age 60 target, need $1.5M (25x $60k), Years to retirement: 30.
Coast FI number = $1,500,000 ÷ (1.07)^30 = $196,730.
Current $150k → Need $46,730 more.
At $70k/year savings rate = 8 months to Coast FI! After reaching $196,730: Can reduce salary to $65k (just covering $50k expenses + taxes).
Work 3 days/week or switch to non-profit job.
By age 60, $196,730 grows to $1,500,000 automatically.
Mathematical Formula: Coast FI Number = Retirement Goal ÷ (1 + Annual Return)^Years Until Retirement.
Example calculations at 7% returns: Age 30 → 65 (35 years): Need $187,000 to reach $2M.
Age 35 → 65 (30 years): Need $262,000 to reach $2M.
Age 40 → 65 (25 years): Need $366,000 to reach $2M.
Age 45 → 65 (20 years): Need $517,000 to reach $2M.
The earlier you start, the less you need for Coast FI.
Common Coast FIRE Milestones: Lean Coast FI: Enough for minimal retirement ($30-40k/year).
Standard Coast FI: Comfortable retirement ($50-70k/year).
Fat Coast FI: Luxury retirement ($100k+ per year).
Barista FI: Coast FI + part-time work covering current expenses (hybrid approach). 2025 Coast FI Strategies: Start aggressive savings in 20s-30s to hit Coast FI by 35-40.
Use employer 401k match even after Coast FI (free money still valuable).
Keep HSA contributions for healthcare (triple tax advantage).
Shift career to passion/purpose work without financial stress.
How do I calculate my Coast FIRE number and when will I reach it?
Calculating Coast FIRE requires four key inputs and backward compound interest math.
Step 1 - Determine Retirement Goal: Annual retirement expenses × 25 (4% rule).
Example: $60,000/year expenses × 25 = $1,500,000 retirement goal.
Step 2 - Calculate Years Until Retirement: Target retirement age - Current age = Years of growth.
Age 35 planning to retire at 65 = 30 years.
Age 40 planning to retire at 60 = 20 years.
Step 3 - Select Expected Annual Return: Conservative: 5-6% (bond-heavy portfolio).
Moderate: 7-8% (balanced 60/40 stocks/bonds).
Aggressive: 9-10% (stock-heavy portfolio).
Standard assumption: 7% real returns (after inflation).
Step 4 - Apply Coast FI Formula: Coast FI Number = Retirement Goal ÷ (1 + Return Rate)^Years.
Example: $1,500,000 ÷ (1.07)^30 = $196,730.
Detailed Example - Age 32 with $100k Saved: Target retirement age: 62 (30 years away).
Desired retirement income: $70k/year ($1.75M goal using 25x rule).
Expected return: 7% annually.
Coast FI calculation: $1,750,000 ÷ (1.07)^30 = $229,686.
Current savings: $100,000.
Gap to Coast FI: $129,686.
Current savings rate: $30k/year.
Time to Coast FI: $129,686 ÷ $30,000 = 4.3 years (age 36).
After Age 36 Reaching Coast FI: Stop all retirement contributions (save $30k/year burden).
Reduce expenses or work less (could drop to $40k salary covering $40k expenses). $229,686 grows to $1,750,000 by age 62 automatically.
Verification check: $229,686 × (1.07)^30 = $1,749,918 ✓.
Coast FI Timeline by Starting Age (assuming 7% returns, $1.5M goal): Age 25 (40 years to 65): Coast FI number $100,434 (very achievable).
Age 30 (35 years to 65): Coast FI number $142,046.
Age 35 (30 years to 65): Coast FI number $196,730.
Age 40 (25 years to 65): Coast FI number $274,538.
Age 45 (20 years to 65): Coast FI number $387,817.
Age 50 (15 years to 65): Coast FI number $543,934.
The younger you start, the lower your Coast FI number (power of compound interest).
Coast FI vs Current Savings - When Will You Reach It: Current $50k, Coast FI target $196k, Saving $20k/year = 7.3 years.
Current $100k, Coast FI target $196k, Saving $30k/year = 3.2 years.
Current $150k, Coast FI target $196k, Saving $40k/year = 1.2 years.
Current $180k, Coast FI target $196k, Saving $25k/year = 0.6 years.
Advanced Calculation - Multiple Retirement Scenarios: Conservative scenario (retire at 70, need $1.2M): Age 35, 35 years to grow, Coast FI = $113,000.
Standard scenario (retire at 65, need $1.5M): Age 35, 30 years to grow, Coast FI = $196,730.
Aggressive scenario (retire at 60, need $1.8M): Age 35, 25 years to grow, Coast FI = $329,430.
Compare your current savings to each scenario to see which Coast FI milestone you have achieved.
Impact of Return Rate Assumptions on Coast FI Number (Age 35, $1.5M goal, 30 years): 5% returns: Coast FI = $346,869 (conservative, need more saved). 6% returns: Coast FI = $260,963. 7% returns: Coast FI = $196,730 (standard assumption). 8% returns: Coast FI = $149,064. 10% returns: Coast FI = $85,910 (aggressive, risky assumption).
Recommendation: Use 6-7% for realistic planning.
Coast FI Progress Tracking: Calculate your FI ratio = Current Savings ÷ Coast FI Number.
Examples: $100k saved ÷ $196k Coast FI target = 51% to Coast FI. $150k saved ÷ $196k target = 76% to Coast FI. $196k saved ÷ $196k target = 100% - Coast FI achieved! Once 100% reached, stop retirement saving immediately, redirect to life enjoyment or career flexibility.
About This Page
Editorial & Updates
- Author: SuperCalc Editorial Team
- Reviewed: SuperCalc Editors (clarity & accuracy)
- Last updated: 2026-01-13
We maintain this page to improve clarity, accuracy, and usability. If you see an issue, please contact hello@supercalc.dev.
Financial/Tax Disclaimer
This tool does not provide financial, investment, or tax advice. Calculations are estimates and may not reflect your specific situation. Consider consulting a licensed professional before making decisions.