Have you already saved enough to retire without contributing another dollar? The Coast FIRE Calculator shows exactly how much you need invested today so compound interest alone grows your portfolio to your full retirement target — no more mandatory savings required. Just let time and markets do the work.
Coast FIRE Calculator
What Is Coast FIRE?
Coast FIRE is a milestone in the Financial Independence, Retire Early (FIRE) movement. You reach it when your invested portfolio is large enough that compound growth alone — with no additional contributions — will carry it to your full retirement target by your planned retirement age. The name comes from "coasting" downhill: once you hit the number, you only need to earn enough to cover today's living expenses. Time and compound interest handle the rest.
Practical example: A 32-year-old who wants to retire at 65 spending $60,000/year needs a $1.5M FIRE number (using the 4% rule). With 7% real returns over 33 years, the growth factor is (1.07)³³ = 9.13. Coast FIRE number = $1,500,000 ÷ 9.13 = $164,000. If they have $164K invested today, they can stop all retirement contributions and still retire on schedule at 65.
The Coast FIRE Formula
Step 1 — Calculate your full FIRE Number:
FIRE Number = Annual Retirement Spending ÷ Safe Withdrawal Rate
Example: $60,000 ÷ 0.04 = $1,500,000
Step 2 — Discount back to today (your Coast FIRE Number):
Coast FIRE = FIRE Number ÷ (1 + Annual Return)^Years Until Retirement
Example: $1,500,000 ÷ (1.07)^33 = $164,000
Coast FIRE Numbers by Age — 2026 Reference Table
Based on $60,000/year retirement spending, 4% withdrawal rate ($1.5M FIRE number), and 7% real annual returns, retiring at age 65:
| Age Now | Years to Retire | Coast FIRE Number | Growth Factor |
|---|---|---|---|
| 25 | 40 years | ~$100,000 | 14.97× |
| 30 | 35 years | ~$142,000 | 10.68× |
| 35 | 30 years | ~$197,000 | 7.61× |
| 40 | 25 years | ~$276,000 | 5.43× |
| 45 | 20 years | ~$388,000 | 3.87× |
| 50 | 15 years | ~$543,000 | 2.76× |
Each 5-year delay requires approximately 40% more invested today to reach the same Coast FIRE milestone.
FIRE Types Compared
| Type | What It Means | Typical Target |
|---|---|---|
| Lean FIRE | Retire on minimal spending (<$40K/year) | $500K–$1M |
| Regular FIRE | Retire on average spending ($40–80K/year) | $1M–$2M |
| Fat FIRE | Retire comfortably ($80K+/year) | $2M–$5M+ |
| Coast FIRE | Stop contributing — let compound growth finish the job | Varies by age |
| Barista FIRE | Work part-time for healthcare + living expenses only | Partial number |
Frequently Asked Questions
What is a Coast FIRE number?
Your Coast FIRE number is the amount you need invested right now so that compound growth alone — with zero additional contributions — grows your portfolio to your full retirement target by your planned retirement age. You calculate it by dividing your FIRE number by (1 + annual return rate) raised to the power of years until retirement.
Is the 4% rule still valid in 2026?
The 4% rule from the 1994 Trinity Study remains widely used and valid for 30-year retirements. It found that a 4% annual withdrawal survived 95% or more of historical 30-year retirement periods. For longer retirements common in early retirement scenarios (40+ years), many financial planners now recommend 3–3.5% for additional safety margin.
What return rate should I use in the calculator?
Most FIRE calculations use 7% as the real (inflation-adjusted) annual return, based on the US stock market's historical long-term average of roughly 10% nominal minus 3% inflation. Use 5–6% for a conservative estimate, or 7–8% if you are comfortable with historical averages and have a long time horizon.
What do I do after hitting Coast FIRE?
After reaching Coast FIRE, you only need to earn enough to cover your current living expenses — no additional investing required. Many people use this milestone to switch to lower-stress jobs, work part-time, travel more, or pursue passion projects while their portfolio coasts to full FIRE entirely through compound growth.
Can I use Coast FIRE without planning to retire early?
Yes. Coast FIRE is a valuable milestone even for traditional retirement at age 65. Hitting your Coast FIRE number in your 30s or 40s means you can redirect previous savings toward other goals — travel, home ownership, family expenses — while remaining fully on track for retirement through compound growth alone.
How is Coast FIRE different from regular FIRE?
Regular FIRE means your portfolio is already large enough to fund retirement immediately at your current withdrawal rate. Coast FIRE means your portfolio is not large enough yet, but will be by the time you retire — without any additional contributions. Coast FIRE is an intermediate milestone you reach years before full FIRE.