Lean FIRE Calculator

Use this calculator to estimate a Lean FIRE target based on lower annual retirement expenses.

What this calculator does

The Lean FIRE calculator estimates the portfolio needed for a minimalist retirement budget. It also estimates the years needed to reach that target from current savings and contributions.

It uses:

• annual lean expenses
• withdrawal rate
• current savings
• annual contribution and expected return

Lean FIRE Formula

Lean FIRE Number = Annual Lean Expenses ÷ (Withdrawal Rate ÷ 100)

Where:

• Annual Lean Expenses = low annual spending target
• Withdrawal Rate = annual portfolio withdrawal percentage
• Lean FIRE Number = required portfolio
• Years to Lean FIRE = time to reach that portfolio

Example calculation

If:

• Annual lean expenses = 36,000
• Withdrawal rate = 4%
• Current savings = 100,000
• Annual contribution = 20,000

Then:

• Lean FIRE number = 36,000 ÷ 0.04
• Lean FIRE number = 900,000
• Monthly expenses = 36,000 ÷ 12
• Monthly expenses = 3,000

The Lean FIRE number is 900,000.

What is Lean FIRE?

Lean FIRE is financial independence based on a lower-cost lifestyle. It usually depends on keeping expenses modest so the required portfolio is smaller.

Why Lean FIRE matters

• lowers the financial independence target
• shows the power of expense control
• may shorten the timeline to independence
• helps evaluate minimalist retirement plans

When to use this calculator

• planning a lower-spending retirement
• comparing lean and standard FIRE targets
• testing a reduced expense budget
• estimating years to financial independence

Common mistakes

• cutting expenses below a realistic level
• ignoring healthcare and housing changes
• assuming lean spending will feel sustainable forever
• leaving no buffer for surprises

Lean FIRE vs FIRE

Lean FIRE uses lower annual expenses than a standard FIRE plan. Standard FIRE usually targets a broader lifestyle budget.

The main difference is spending level, not the underlying formula.

FAQs

What is Lean FIRE?

Lean FIRE is financial independence based on a minimalist or lower-cost annual spending level.

How do you calculate Lean FIRE?

Divide annual lean expenses by the withdrawal rate, then estimate years to reach that portfolio.

What is a good Lean FIRE number?

A good Lean FIRE number fully covers realistic essential expenses with a safety margin.

What is the difference between Lean FIRE and FIRE?

Lean FIRE targets a smaller budget. FIRE can represent a broader or more typical spending plan.