Coast FI Calculator
Wondering when you can stop contributing to investments and still reach full FIRE later? This Coast FI calculator estimates the earliest age you can stop saving and let your portfolio grow on its own, while still hitting your FIRE number by your chosen target age.
Your FIRE number is $1,500,000, based on $60,000 of annual retirement income and a 4.00% withdrawal rate.
With your current cashflow, you contribute $15,000 per year.
You hit Coast FI at age 37.
That means: if you save until age 37 and then contribute $0 after that, your investments are projected to still reach your FIRE number by age 65.
Real return used: 8.00% (return - inflation).
Tip: Coast FI moves a lot when you change your savings rate or your target age. Try adjusting expenses, take home pay, and the “FI by age” to see how sensitive your result is.
Important note on the Coast FI calculator: Values shown here are estimates for general planning. Real market returns are unpredictable, and your income and expenses can change over time. This tool is not financial, tax, or legal advice. Consider speaking with a qualified professional for guidance specific to your situation.
How this Coast FI calculator works
This tool is built around one question.
When will I have enough invested that I can stop contributing, and still reach full FIRE by a future age?
It starts by estimating how much you are currently able to invest each year:
Annual contribution = max(0, take home pay - current annual expenses)
Then the calculator projects your invested net worth over time if you keep contributing that amount. At every age, it also computes how much you would need invested at that age to coast to your FIRE number by your selected target age.
To interact with the chart, hover over it to see values at each age.
What the chart lines mean
Keep saving (blue):
Your projected invested net worth if you keep contributing your current amount each year.
Coast path (green):
A path that assumes you keep contributing until you hit Coast FI, and then contribute $0 after that. From that point on, growth does the work.
Required to coast (purple dashed):
The amount you would need invested at each age to be able to stop contributing and still reach your FIRE number by your target age.
FIRE target (red dashed):
Your FIRE number. This is the portfolio size that supports your desired retirement income using your chosen withdrawal rate.
Coast FI marker (vertical line):
The earliest age where your “keep saving” line meets the “required to coast” line. That is your Coast FI age.
What is Coast FI?
Coast FI is a milestone on the FIRE path.
You have enough invested that, even if you stop contributing, your portfolio can still grow to full financial independence by a later age.
This does not mean you can fully retire right away. It means your savings contributions become optional. After you hit Coast FI, you might choose to:
- keep saving and reach FIRE sooner
- reduce hours or take a lower stress job
- step away for a sabbatical
- redirect savings toward other goals like a home or kids
If you are new to FIRE, you may want to read: What is FIRE?
Coast FI vs Barista FIRE
Coast FI and Barista FIRE are related, but they are not the same thing.
Coast FI: you stop contributing to investments and let the portfolio grow over time.
Barista FIRE: you keep working in some form, often part time, and that income helps pay expenses while investments keep growing.
In real life, people often combine them. For example, someone might hit Coast FI first, then switch to lighter work until they reach full FIRE.
The FIRE number
Coast FI still uses the same destination as traditional FIRE. The destination is your FIRE number.
This calculator uses:
FIRE number = desired annual retirement income ÷ withdrawal rate
Example:
If you want $60,000 per year in retirement and you use a 4% withdrawal rate:
60,000 ÷ 0.04 = $1,500,000
So the FIRE number is about $1.5M in today’s dollars.
Why the FIRE line stays flat
The chart is displayed in today’s dollars to keep things easier to interpret.
To do this, the calculator uses a real return estimate:
Real return = investment return - inflation
This keeps the FIRE target from rising over time due to inflation, and it lets you compare paths using purchasing power instead of raw future dollars.
Assumptions this calculator makes
This is a simplified planning tool, so it makes a few assumptions:
- You invest your contribution each year
- Contribution is take home pay minus annual expenses, but not less than zero
- Returns are smoothed using a steady return assumption
- Spending is stable in real terms (today’s dollars)
- Taxes, healthcare, and Social Security are not included
If you want to be conservative, use a lower return assumption, a lower withdrawal rate, or a higher retirement income target.
Frequently Asked Questions
What does it mean to “hit Coast FI”?
It means your portfolio is large enough that you can stop contributing, and it can still grow to your FIRE number by your target age. It is a milestone, not full retirement.
Is Coast FI the same as Lean FIRE?
No. Lean FIRE is about retiring fully on a smaller spending level. Coast FI is about reaching the point where you no longer need to contribute, even if you are not fully retired yet.
What if my contribution is zero?
If your take home pay is less than or equal to your expenses, your contribution is assumed to be $0. In that case, Coast FI may already be true (if you have enough invested), or it may be out of reach without changing inputs.
Does this include taxes?
No. This is a simplified model. Taxes and other real world costs can change results a lot.
What withdrawal rate should I use?
Many people start with 4%, but it depends on your timeline and flexibility. A lower withdrawal rate increases your FIRE number. A higher withdrawal rate decreases it. If you want a conservative plan, use a lower withdrawal rate.
Learn more about Coast FIRE
Scenarios, tradeoffs, and comparisons.
Coast FIRE By Age - How much do you need at 25, 35, 45?
→How much do you need to have saved at different ages to achieve Coast FIRE? Use our interactive tools, examples, and projections to explore targets for ages 25, 35, 45, and beyond.
12 min read · Updated 02/04/2026
How much do you need saved to Coast FIRE?
→Exactly how much do you need saved to reach Coast FIRE? We break down the numbers and show you how to calculate your own Coast FIRE target.
14 min read · Updated 02/02/2026
What Is Coast FIRE (with graph and examples)
→Coast FIRE is a form of financial independence where you invest aggressively early on so your investments can grow to cover your retirement without additional saving. Learn how it works, how much you need, and whether it fits your lifestyle.
8 min read · Updated 01/25/2026
Barista FIRE vs Coast FIRE: Key Differences and How to Choose
→Compare Barista FIRE vs Coast FIRE to understand how each approach works, how much you need saved, and which strategy fits your lifestyle and income goals.
12 min read · Updated 01/15/2026