Your FI (Financial Independence) number is the portfolio size at which your investments generate enough passive income to cover your expenses indefinitely — so work becomes optional. It's typically 25× your annual spending (based on the 4% rule).

How do I calculate my FI number?

Multiply your expected annual spending in retirement by 25 (or divide by your target withdrawal rate). If you plan to spend $50,000/year, your FI number is $1.25 million. This calculator adjusts for Social Security, pensions, and other income sources.

How can I reach FI faster?

The two biggest levers are savings rate and investment returns. Increasing your savings rate from 15% to 30% can cut your time to FI roughly in half. Reducing lifestyle expenses has a double effect: it lowers your FI number AND increases your savings rate.

Coast FI is the point where you have enough invested that — without adding another dollar — compound growth alone will reach your FI number by traditional retirement age. After hitting coast FI, you only need to earn enough to cover current living expenses.

FI Number Calculator

Find the portfolio size that makes work optional, the years to get there at your current savings pace, and the Coast FI balance that lets growth do the rest.

Your FI number

$1,250,000

At 4% SWR you can sustainably withdraw $50,000/year. Reach FI in roughly 23.1 years.

Years to FI

23.1

Coast FI today

$405,313

Balance at 23y

$1,341,627

Portfolio balanceCumulative contributionsFI number

What is Financial Independence?

Financial Independence (FI) means having enough invested to cover your living expenses indefinitely. You're not forced to work for money — you can work because you want to, take risks you couldn't otherwise afford, or stop altogether. The FI number is calculated by dividing your annual spending by your safe withdrawal rate, which is typically 4%.

Coast FI is a variant: it's the balance you'd need today such that, with zero additional contributions, compound growth alone will grow that amount to your full FI number by traditional retirement age. Once you hit Coast FI, you only need to earn enough to cover your daily expenses — your investments take care of retirement.

Why it matters to your money

The FI number gives you a concrete target. Instead of vaguely "saving for retirement," you have a specific dollar amount and timeline. The most powerful insight from FIRE math is that savings rate matters more than income or investment returns. Going from saving 20% to 40% of your income roughly halves your time to FI. Reducing expenses has the same double effect: it lowers your FI number and boosts your savings rate simultaneously.

Read the full explainer on the FIRE movement for background on the philosophy, different FI strategies (LeanFIRE, BaristaFIRE, Coast FI), and how people transition from working to FI.

Rules of thumb

Your spending determines your FI number, not your income: A $60K/year spender needs $1.5M (at 4% SWR). A $100K/year spender needs $2.5M. Lower spending = faster FI.
Savings rate is the biggest lever: At 15% savings rate, FI takes ~30 years. At 30%, about 20 years. At 50%, about 13 years. Each 5% increase in savings rate shaves roughly 2–3 years off your timeline.
Coast FI is often achievable faster than full FI: Many people find their Coast FI balance within 10–15 years of working, at which point they can enjoy more financial flexibility while the investments grow.

Frequently asked questions

What is a FI number?: Your FI (Financial Independence) number is the portfolio size at which your investments generate enough passive income to cover your expenses indefinitely — so work becomes optional. It's typically 25× your annual spending (based on the 4% rule).
How do I calculate my FI number?: Multiply your expected annual spending in retirement by 25 (or divide by your target withdrawal rate). If you plan to spend $50,000/year, your FI number is $1.25 million. This calculator adjusts for Social Security, pensions, and other income sources.
How can I reach FI faster?: The two biggest levers are savings rate and investment returns. Increasing your savings rate from 15% to 30% can cut your time to FI roughly in half. Reducing lifestyle expenses has a double effect: it lowers your FI number AND increases your savings rate.
What is 'coast FI'?: Coast FI is the point where you have enough invested that — without adding another dollar — compound growth alone will reach your FI number by traditional retirement age. After hitting coast FI, you only need to earn enough to cover current living expenses.