What is the main difference between Coast FIRE and Lean FIRE?

Coast FIRE focuses on front-loading your savings early so compound interest does the rest—you still work but only to cover current expenses. Lean FIRE means fully retiring but on a minimal budget, typically under $40,000/year.

How do I calculate my Coast FIRE number?

Your Coast FIRE number depends on your target retirement age, expected investment returns, and desired retirement spending. Use the formula: Coast Number = Target FIRE Number ÷ (1 + annual return)^(years until traditional retirement). Our calculator handles this automatically.

Is Lean FIRE sustainable long-term?

Lean FIRE can be sustainable if you genuinely enjoy a minimalist lifestyle and have low-cost hobbies. However, it has less margin for unexpected expenses like healthcare or inflation spikes. Consider building a buffer or having flexible spending categories.

Can I combine Coast FIRE and Lean FIRE strategies?

Absolutely. Many people save aggressively (Lean FIRE mindset) to hit their Coast number early, then switch to a lower-stress job while their investments compound. This hybrid approach offers flexibility and reduced burnout.

Which strategy is better for someone in their 20s?

Coast FIRE often works well for young savers because you have decades for compound growth. Save aggressively for 10-15 years, hit your Coast number, then enjoy career flexibility. Lean FIRE might suit those who want to exit the workforce entirely ASAP.

What are the biggest risks of each strategy?

Coast FIRE risks include poor market returns during your coasting years or lifestyle inflation. Lean FIRE risks include unexpected expenses, healthcare costs, or finding the frugal lifestyle unsustainable over decades.

Coast FIRE vs. Lean FIRE
Choosing Your Path to Freedom

Traditional FIRE requires a massive nest egg. But what if you could retire sooner by tweaking the variables? Enter Coast FIRE and Lean FIRE—two powerful strategies for those who want freedom without the wait.

The Quick Summary

Not sure which one fits you? Here is the high-level breakdown:

🏖️ Coast FIRE

Goal: Save enough early so compound interest covers your retirement.
Lifestyle: Work to cover current expenses only.
Best For: Young professionals with high savings rates who want to "downshift" careers later.

🌱 Lean FIRE

Goal: Retire completely on a smaller budget (e.g., $30k-$40k/year).
Lifestyle: Minimalist, frugal, simple living.
Best For: People who hate their jobs and value time over luxury.

Deep Dive: Coast FIRE

Coast FIRE is about reaching a "tipping point" where you no longer need to contribute to your retirement accounts. Your existing investments, left alone to compound for 10-20 years, will grow into a full retirement fund.

Once you hit your Coast number, you only need to earn enough money to pay your monthly bills. This opens the door to:

Switching to a lower-stress job
Working part-time
Taking sabbaticals

Coast FIRE vs. Standard Path

Comparing heavy early savings (Coast) vs. consistent saving (Standard)

Simulation assumes 7% returns. Standard: Save $10k/yr (age 25-65). Coast: Save $30k/yr (age 25-35), then $0.

Deep Dive: Lean FIRE

Lean FIRE attacks the equation from the expense side. By drastically lowering your cost of living, you lower your required FIRE number.

If you can live happily on $35,000 a year, you "only" need $875,000 to retire (based on the 4% rule). Compare that to a "Fat FIRE" lifestyle spending $100,000, which requires $2.5 million. Lean FIRE is the fastest path out of the workforce, but it requires discipline.

Run The Numbers

The best way to decide is to see the math. Use our calculator to simulate both scenarios:

For Coast FIRE: Input your current age and a "Coast Age" (e.g., 35). See if your current balance grows enough by age 60 without adding more.
For Lean FIRE: Lower your "Desired Monthly Allowance" to a minimalist level and see how fast you reach freedom.

Which Should You Choose?

You don't have to pick one today. Many people start with a Lean FIRE mindset to save aggressively, then transition to Coast FIRE once they have a safety net, allowing them to enjoy their 30s and 40s more.

The most important step is to just start.

Frequently Asked Questions

Written by The InvestingFIRE Team

We are a group of financial data enthusiasts and early retirees dedicated to building the most accurate FIRE tools on the web. Our goal is to replace guesswork with math.