Your Financial Independence Number: What It Is and How to Calculate It

There is a number that changes everything. It is the number that tells you exactly how much money you need invested before your money starts working harder than you do. Once your portfolio hits that number, you no longer have to work for a paycheck. Work becomes a choice, not a requirement.

That number is called your Financial Independence Number, and the good news is that calculating it is simpler than most people think. No complex spreadsheets. No finance degree required. Just one formula and a few minutes of honest math.

Here is how it works.

What Is a Financial Independence Number?

Your Financial Independence Number (sometimes called your FI number or FIRE number) is the total amount of invested assets you need to cover your living expenses indefinitely, without ever running out of money.

The concept became mainstream through what is known as the Trinity Study, a research project from the late 1990s that analyzed decades of market data to figure out how much retirees could safely withdraw each year without depleting their portfolio. The study found that withdrawing 4% of your portfolio per year gives you an extremely high likelihood of your money lasting 30 years or more, even accounting for market downturns.

That 4% figure is called the Safe Withdrawal Rate, and it is the foundation of the FI number calculation.

The 25x Rule: The Formula Behind Financial Independence

If you can withdraw 4% of your portfolio per year and that covers your expenses, then your FI number is simply your annual expenses multiplied by 25. Here is why: if 4% of your portfolio equals your annual expenses, then your total portfolio must be 25 times those expenses (because 1 divided by 0.04 equals 25).

This is the 25x Rule, and it is the cleanest financial formula you will ever use.

FI Number = Annual Expenses x 25

That is it. Your spending determines your target, not your income. Two people earning the same salary can have wildly different FI numbers based entirely on how much they spend each year.

How to Calculate Your FI Number in Three Steps

Let us walk through this with real numbers so it actually lands.

Step 1: Figure out your true annual expenses. Add up everything you spend in a year, including rent or mortgage, groceries, utilities, transportation, subscriptions, travel, dining out, and anything else that comes out of your account. Be honest here. This is not a budget exercise. You are just capturing what you actually spend today.

If you are not sure, pull the last three months of bank and credit card statements and multiply by four. That gives you a solid annual estimate.

Step 2: Multiply by 25. Take that annual expense number and multiply it by 25. The result is your FI number, the portfolio size that can fund your lifestyle forever without you lifting a finger.

Step 3: Adjust for what you want your future lifestyle to look like. Your FI number does not have to match your current spending. If you plan to travel more in retirement, build that in. If you expect your mortgage to be paid off, subtract that payment. The goal is to calculate the annual expenses you expect to have once you are financially independent, then multiply by 25.

Real-World Examples for Young Professionals

Here is what the 25x rule looks like for three different income and lifestyle scenarios that are common for the people FirstStep Financials works with.

Example A: The Minimalist Couple. Annual expenses: $60,000. FI Number: $60,000 x 25 = $1,500,000.

Example B: The Single Professional in a Mid-Cost City. Annual expenses: $80,000. FI Number: $80,000 x 25 = $2,000,000.

Example C: The Growing Family. Annual expenses: $120,000. FI Number: $120,000 x 25 = $3,000,000.

These numbers can feel large at first glance. But here is the important context: these are invested portfolio totals, and compound growth does the heavy lifting over time. A 35-year-old investing $2,500 per month into diversified index funds, assuming an average annual return of 7% after inflation, reaches $2 million in roughly 25 years. That is financial independence by 60, or earlier if contributions increase.

How Your FI Number Connects to the Three-Bucket Strategy

Knowing your FI number is the destination. The three-bucket investing strategy is how you get there efficiently.

At FirstStep Financials, we structure every client's investing approach around three types of accounts, each with a different tax treatment:

Bucket 1: Tax-Deferred (401k, Traditional IRA). You invest pre-tax dollars, your money grows without being taxed each year, and you pay taxes when you withdraw in retirement. These accounts reduce your taxable income now and let your investments compound faster.

Bucket 2: Tax-Free (Roth IRA, Roth 401k). You invest after-tax dollars, but your money grows completely tax-free and withdrawals in retirement are tax-free. This is the most powerful bucket for long-term wealth because you never pay taxes on the growth.

Bucket 3: Taxable Brokerage. No contribution limits, no restrictions on withdrawals. You invest after-tax dollars and pay capital gains taxes on growth, but the flexibility is unmatched. For people pursuing early financial independence, this bucket is critical because it can be accessed before age 59 1/2 without penalty.

Building toward your FI number means filling all three buckets strategically. Maximize tax-advantaged accounts first, then direct remaining investment dollars into your taxable brokerage. Over 20 to 30 years, this approach produces significantly more wealth than putting everything in one place.

How to Reach Your FI Number Faster

There are really only two levers: spend less or earn more. But within those two levers, there are several moves that make a meaningful difference.

Reduce your annual expenses strategically. Even cutting $10,000 per year in spending reduces your FI number by $250,000 (because you also need 25 times less). Every dollar you do not spend is worth 25 dollars toward your target.

Increase your savings rate. The percentage of your income you save is the single biggest driver of when you reach financial independence. Someone saving 10% of their income may take 40 years to retire. Someone saving 40% could get there in 15 to 20. Time in the market beats everything else.

Automate your investments. Set up automatic contributions to all three buckets so the money moves before you can spend it. This removes willpower from the equation and turns wealth-building into a background process. Systems beat discipline every time.

Invest in low-cost index funds. High investment fees quietly destroy wealth over decades. A 1% annual fee on a $1 million portfolio costs $10,000 per year, money that never compounds. Index funds give you broad market exposure with minimal costs.

Grow your income and keep expenses flat. Every raise, bonus, or side income stream that flows directly into investments dramatically accelerates your timeline. Lifestyle inflation is the silent enemy of financial independence.

The Number Is Not the Finish Line. It Is the Starting Line.

Your FI number gives you a target, and targets change everything. When you know exactly how far you are from financial independence, every financial decision becomes clearer. Do you really need the upgraded car lease, or does that $300 per month make more sense going into your Roth IRA? Does that subscription you barely use serve you, or does it silently push your FI date back?

Most people spend their entire careers never calculating this number. They work, they spend, and they hope it all works out. FirstStep Financials was built to help young professionals and young families do something different: build a real system, automate real habits, and actually reach financial freedom with a plan.

If you don’t know your number, you’re guessing your future. Start by calculating it today, then let’s build a clear path to get you there.

Build Habits. Grow Wealth. Live Well.