The 4% rule, from the 1998 Trinity Study, states that a portfolio invested in a mix of stocks and bonds can support annual withdrawals of 4% of the initial balance indefinitely. It means you need 25x your annual expenses saved before retiring.

Should I use 4% or a lower withdrawal rate?

The classic 4% is calibrated for a 30-year retirement horizon. For very early retirees expecting 40 or 50 years of retirement, many FIRE practitioners use 3.25%–3.5% for extra safety. You can adjust the rate in this calculator.

Does the FIRE number account for inflation?

Yes, when you use the default 7% return rate, that figure is already an approximate inflation-adjusted (real) return for a diversified stock portfolio. Your FIRE number is expressed in today's dollars.

What counts as annual expenses?

Include all recurring costs: housing, food, utilities, transportation, health insurance, travel, entertainment, and any other spending. In retirement, exclude work-related costs (commuting, work clothes) but add healthcare if your employer currently covers it.

Is Social Security included?

No. This calculator focuses on the portfolio needed to fund 100% of your expenses. If you expect Social Security or pension income, subtract that amount from your annual expenses before entering it to get a more accurate FIRE number.

What is Lean FIRE vs Fat FIRE?

Lean FIRE means retiring on a very frugal budget (often under $40,000/year), while Fat FIRE means retiring with a comfortable or even luxurious lifestyle ($100,000+/year). Both use the same 25x rule — the difference is purely in your target annual spending.

Coast FIRE is the point where your invested savings will grow to your full FIRE number by traditional retirement age without any new contributions. You still work to cover current expenses, but you no longer need to save for retirement — compound growth alone carries you there.

FIRE Number Calculator

Enter your annual expenses to instantly calculate the portfolio size needed to retire using the 4% safe withdrawal rate rule.

Your FIRE Inputs

Annual Expenses in Retirement ($)

All living costs per year in today's dollars.

Safe Withdrawal Rate (%)

Classic 4% = 25x expenses. Use 3.5% for 40+ year horizons.

Optional — Time to FIRE

Current Savings / Portfolio ($)

Annual Contributions ($)

How much you invest per year going forward.

Expected Annual Return (%)

Inflation-adjusted return. 7% is a common estimate for diversified stocks.

Your FIRE Number

$1,250,000 needed to retire

Annual Expenses

$50,000

Withdrawal Rate

4.0%

Multiplier

25x

Time to Financial Independence

Current Portfolio 4% of FIRE goal

$50,000 $1,250,000

Years to FIRE

—

Target Year

—

Portfolio Milestones

Milestone	Portfolio	Year Reached

Summary

The FIRE number is the total investment portfolio value that allows you to retire and live off withdrawals indefinitely. It is derived from the Trinity Study, which found that a 4% annual withdrawal rate has a very high probability of lasting 30 or more years across historical market conditions. Your FIRE number equals your planned annual expenses divided by 0.04, meaning you need 25 times your annual spending saved.

How it works

Enter your estimated annual expenses in retirement.
Optionally adjust the safe withdrawal rate (default 4%).
Enter your current savings and annual savings to see years to FIRE.
Adjust expected annual investment return (default 7%, inflation-adjusted).
The calculator shows your FIRE number, time to reach it, and a savings progress chart.

Use cases

Determining the exact portfolio size needed to retire early.
Comparing FIRE timelines at different spending levels.
Modeling how cutting expenses accelerates financial independence.
Planning contribution rates to hit a specific FIRE target date.
Understanding the impact of different safe withdrawal rates on required savings.
Exploring lean FIRE vs fat FIRE retirement scenarios.

Frequently Asked Questions

Last updated: 2026-05-23 · Reviewed by Nham Vu