Both FIRE and Coast FIRE are milestones on the same path to financial independence — but they answer two very different questions.
- FIRE asks: Have I saved enough to live off my investments now?
- Coast FIRE asks: Have I saved enough that I can stop saving and still retire on time?
This article explains the difference, shows the formulas behind each, and walks through worked examples for both.
FIRE in One Sentence
FIRE (Financial Independence, Retire Early) is achieved when:
Portfolio ≥ Annual Expenses × 25
The 25× multiplier follows the 4% safe withdrawal rate popularised by the 1998 Trinity Study. Once you cross your FIRE number, work is optional. See our full primer on what FIRE is and how it works for the background.
Coast FIRE in One Sentence
Coast FIRE is achieved when your current portfolio, left alone (no further contributions), will compound into your full FIRE number by traditional retirement age.
Coast FIRE Number = FIRE Number ÷ (1 + r)^n
Where:
- r = expected real annual return (e.g., 5%)
- n = years until traditional retirement (e.g., 65 − your age)
Past the Coast FIRE milestone, you still need to earn enough to cover today's living costs — but you no longer need to save for retirement. Your future self is already funded.
Side-by-Side
| FIRE | Coast FIRE | |
|---|---|---|
| Goal | Stop working entirely | Stop saving for retirement |
| Required portfolio | 25× annual expenses | Discounted FIRE number |
| Income still needed? | No — investments cover expenses | Yes — must cover current spending |
| Typical age reached | 35–55 | 30–45 |
| Risk if returns disappoint | Higher (must withdraw) | Lower (still working) |
Worked Example — FIRE
Asha, age 32, spends $60,000/year.
- FIRE Number = $60,000 × 25 = $1,500,000
If she invests $30,000/year at a 6% real return, she reaches $1.5M in about 23 years, at age 55. Use the FIRE Calculator to model your own numbers.
Worked Example — Coast FIRE
Same Asha, same FIRE number ($1,500,000), traditional retirement at 65.
- Years to compound: 65 − 32 = 33
- Coast FIRE Number = $1,500,000 ÷ (1.06)^33 ≈ $1,500,000 ÷ 6.84 ≈ $219,300
If Asha can build a $219,300 portfolio by 32 and leave it alone, it will grow to roughly $1.5M by 65 — without another dollar of contributions. From that point she only needs to cover today's living costs. Run the numbers in the Coast FIRE Calculator.
How to Decide Which Milestone You're Targeting
- Choose FIRE if you want to stop working entirely and live off investments. Be ready to manage sequence-of-returns risk, healthcare costs and tax-efficient withdrawals.
- Choose Coast FIRE if you like your work but want flexibility — to take a lower-paying job, switch careers, take a sabbatical, or work part-time without falling behind on retirement.
Many people hit Coast FIRE on the way to FIRE — at which point savings become a lifestyle choice rather than a requirement.
Benefits of Each
FIRE benefits
- Full financial freedom
- No requirement to earn an income
- Time freedom early in life
Coast FIRE benefits
- Reached much earlier
- Reduces savings pressure during high-spend life phases (children, mortgage)
- Less reliant on the 4% rule because the portfolio keeps compounding
Common Mistakes
- Confusing nominal and real returns. Coast FIRE math should use real (inflation-adjusted) returns — typically 4–6%.
- Forgetting to cover current expenses post–Coast FIRE. You stop saving, you do not stop earning.
- Overestimating returns. Even a 1% lower return materially raises the Coast FIRE number, because compounding is exponential in r.
- Ignoring tax shelters. RRSPs, 401(k)s, ISAs and TFSAs all change after-tax compounding. Run the math after tax, not before.
Frequently Asked Questions
Is Coast FIRE risky? Less risky than full FIRE — you still earn an income and can react to market downturns. The risk is that long-run returns disappoint, requiring a return to saving.
Can I Coast FIRE and contribute later if needed? Yes. Coast FIRE is a state, not a contract. Many people switch between coasting and contributing as life circumstances change.
Which is better for parents in their 30s? Coast FIRE often suits people in expensive life phases. Hitting Coast FIRE early frees up future income for childcare, housing or education without derailing retirement.
What return rate should I assume? Most planners use a 5% real return (about 7% nominal minus 2% inflation). Conservative planners use 4%.
Related Calculators
- FIRE Calculator
- Coast FIRE Calculator
- Retirement Savings Calculator
- RRSP Calculator and TFSA Calculator
Conclusion
FIRE and Coast FIRE measure two different things. FIRE asks whether you can stop working. Coast FIRE asks whether you can stop saving. Most people will cross Coast FIRE long before FIRE — and that earlier milestone can be the more valuable one because it buys decades of flexibility while your portfolio quietly compounds.
Educational only — not financial advice. Verify retirement and tax rules with your local regulator or a licensed advisor.