Coastfire Calculator

Your Coast FIRE Number Is

$0

Yearly Portfolio Projection

Age	Year	Starting Balance	Contribution	Investment Growth	Ending Balance

What is Coast FIRE?

Coast FIRE is a milestone on the path to financial independence. It’s the point where you have enough money in your retirement accounts that, without contributing another cent, your portfolio will grow to support a traditional retirement. Once you reach your Coast FIRE number, your investments are projected to do all the heavy lifting for you, “coasting” to your full retirement goal thanks to compound growth.

This doesn’t mean you retire immediately. Instead, it means you no longer *have* to save for retirement. You only need to earn enough to cover your current living expenses. This frees you up to pursue a passion project, switch to a less stressful job, work part-time, or start a business, all without sacrificing your future retirement security. This makes the coastfire calculator an essential tool for lifestyle design.

The Coast FIRE Formula and Explanation

Calculating your Coast FIRE number involves two main steps. First, you determine your total retirement need (your FIRE number), and second, you discount that amount back to today’s value. Our coastfire calculator automates this for you.

The core formulas are:

1. Full Retirement Nest Egg = Annual Retirement Spending / (Safe Withdrawal Rate / 100)
2. Coast FIRE Number = Full Nest Egg / (1 + Annual Investment Return)^{Years to Retirement}

This tells you the exact amount you need invested *today* to grow into your full nest egg by retirement age.

Formula Variables

Variable	Meaning	Unit	Typical Range
Annual Retirement Spending	The amount of money you expect to live on per year in retirement.	Currency ($)	$40,000 – $150,000
Safe Withdrawal Rate	The percentage of your portfolio you can withdraw each year without running out of money. Check out our SWR calculator for more.	Percentage (%)	3.5% – 4.5%
Annual Investment Return	The average yearly growth rate you expect from your investments, before inflation.	Percentage (%)	6% – 8%
Years to Retirement	The time horizon until you plan to fully retire (Retirement Age – Current Age).	Years	20 – 40 years

Practical Examples

Example 1: The Early Saver

Sarah is 30 years old with $100,000 already invested. She wants to retire at 65 and expects to spend $60,000 a year. Using a 4% SWR and a 7% expected return, her numbers look like this:

• Full Nest Egg Needed: $60,000 / 0.04 = $1,500,000
• Years to Grow: 65 – 30 = 35 years
• Coast FIRE Number: $1,500,000 / (1 + 0.07)³⁵ = $140,462

Since Sarah already has $100,000, she only needs to invest about $40,000 more to hit her Coast FIRE number. Once she does, she can stop saving for retirement entirely!

Example 2: A Later Start

Mike is 40 with $150,000 invested. He also wants to retire at 65 and spend $60,000 annually. Using the same rates:

• Full Nest Egg Needed: $1,500,000
• Years to Grow: 65 – 40 = 25 years
• Coast FIRE Number: $1,500,000 / (1 + 0.07)²⁵ = $275,699

Mike needs about $125,000 more to reach his Coast FIRE number. Because he has 10 fewer years for his money to compound, his target is significantly higher than Sarah’s.

How to Use This Coast FIRE Calculator

Our tool is designed to be a comprehensive yet simple coastfire calculator. Follow these steps for an accurate projection:

1. Enter Your Ages: Input your current age and your desired full retirement age.
2. Define Your Finances: Fill in your current invested assets and what you plan to spend annually in retirement. Be realistic with your spending; it’s a critical input.
3. Set Growth Assumptions: Enter your expected annual return and your planned safe withdrawal rate. The 4% rule is a common starting point for the SWR.
4. Add Contributions: Enter your planned annual retirement contribution to see how quickly you can reach your Coast FIRE number. Set this to $0 to see if you’ve already hit it.
5. Analyze the Results: The calculator will instantly show your Coast FIRE number, your total retirement nest egg, and a status message telling you how far you have to go. The chart and table visualize your journey year by year.

Key Factors That Affect Your Coast FIRE Number

• Starting Age: The younger you are, the more powerful compounding is, and the lower your Coast FIRE number will be.
• Investment Returns: A higher average return means your money grows faster, reducing the principal you need. A good investment growth calculator can show this effect.
• Time Horizon: The more years you have until retirement, the less you need to have invested today.
• Retirement Spending: Lower planned spending directly reduces the size of the nest egg you need, making your Coast FIRE number much easier to achieve.
• Inflation: While not a direct input in this simplified calculator, higher inflation erodes returns. Experts often suggest using a “real return” (investment return minus inflation) of 5-7% for conservative planning.
• Safe Withdrawal Rate: A lower SWR (e.g., 3.5%) is more conservative and requires a larger nest egg, thus increasing your Coast FIRE number.

Frequently Asked Questions (FAQ)

1. What does it mean if my current portfolio is higher than my Coast FIRE number?

Congratulations! It means you have officially reached Coast FIRE. You can theoretically stop making new retirement contributions, and your existing portfolio should grow enough on its own to fund your retirement.

2. Can I retire when I hit my Coast FIRE number?

No. Coast FIRE is not full retirement. It means you can stop *saving* for retirement, but you still need to earn enough to cover your current living expenses until your target retirement age.

3. How is Coast FIRE different from Barista FIRE?

Coast FIRE is about having enough invested to let it grow untouched. Barista FIRE typically means you retire from your primary career but take a part-time job (like at a coffee shop) that offers health insurance and covers some living expenses, allowing you to touch your retirement funds sooner or in greater amounts. Learn more with a Barista FIRE calculator.

4. What should my expected annual investment return be?

A conservative estimate is typically 6-8% for a diversified stock portfolio, which accounts for an average historical return of 9-10% minus 2-3% for inflation. Your own risk tolerance will determine the right number.

5. What is a “safe” withdrawal rate?

The 4% rule, based on the Trinity Study, is a common benchmark, suggesting you can withdraw 4% of your initial portfolio value each year (adjusted for inflation) with a very low chance of running out of money over 30 years.

6. Does this calculator account for taxes?

No, this coastfire calculator uses pre-tax numbers for simplicity. Your actual results will vary depending on whether your investments are in tax-advantaged accounts (like a 401k or IRA) or taxable brokerage accounts.

7. Why did my Coast FIRE number get so much higher when I increased my retirement age?

This is a common point of confusion. If you push retirement further away, you might think you need less money now. However, the calculation is based on having a nest egg ready at a specific age. If you change that age, the target changes. The key is to compare your current portfolio to the Coast FIRE number for *your target retirement age*.

8. What happens after I reach Coast FIRE?

You have options! You can downshift your career, pursue hobbies, or even continue working and saving to reach full financial independence even sooner. The choice is yours. This milestone is about creating flexibility. It’s the core of the FIRE movement.