FI Number Calculator

Your FI number is the size of portfolio that could pay for your life without a paycheck. For healthcare professionals, reaching it isn't necessarily about retiring early. It's about having choices — to cut back hours, leave a job that's burning you out, or work because you want to.

What this calculator does

Enter what you expect to spend each year in retirement (in today's dollars), any other retirement income like a pension or Social Security, a withdrawal rate, what you've already invested, how much you invest each year and your expected return after inflation. It shows:

• your FI number,
• how many years it will take to reach it,
• your progress so far, and
• how soon you could stop saving and let growth carry you to your goal within 30 years (sometimes called "Coast FI").

The chart shows your portfolio growing toward your FI number.

The formula in plain English

FI number = (annual spending − other retirement income) ÷ withdrawal rate.

At a 4% withdrawal rate, that's 25 times what your portfolio needs to cover each year. At 3.5%, it's about 28.6 times.

Years to FI: each year, your portfolio grows by your real return and you add your annual savings. The calculator counts the years until the balance reaches your FI number.

Everything is in today's dollars, so you don't have to guess at inflation separately.

A worked example

Chris is a pharmacist and his wife is a physical therapist. They expect to spend $120,000 a year in retirement and to receive about $30,000 a year from Social Security, so their portfolio needs to cover $90,000. At a 4% withdrawal rate:

• FI number: $2,250,000.
• They have $200,000 invested (about 9% of the way) and invest $60,000 a year.
• At a 5% real return, they reach FI in about 19 years.
• After about seven years of saving, growth alone could carry them to the goal within 30 years — so the pressure eases sooner than they expected.

Why it matters at each career stage

If you're: Student

You're early, and that's an advantage. Small amounts invested now have decades to compound. Focus on keeping debt reasonable and learning the basics.

If you're: Resident / fellow

Your FI number may feel far away. Even so, a Roth IRA in training and a clear picture of your future spending help you avoid lifestyle creep when your income jumps.

If you're: Employed

This is when FI is won or lost. The biggest lever isn't investment returns; it's the gap between income and spending. Raising your savings rate from 15% to 25% can take years off your timeline.

If you're: Practice owner

Your practice may be part of your FI plan, but don't count on a sale price. Treat retirement accounts and investments as your base and any practice sale as a bonus.

Choosing a withdrawal rate

The withdrawal rate is the biggest assumption in the calculation, so it's worth a moment of thought. A 4% rate has historically held up for 30-year retirements with a balanced portfolio. If you might stop working in your 40s or 50s, your money may need to last 40 years or more, and a 3.25%–3.5% rate gives more margin. If you'll have a pension, part-time income or flexibility to cut spending in bad markets, 4% may be fine. Try a few rates and see how much the target moves — that range is more useful than a single number.

How to use your FI number

Lower spending counts twice. Every $1,000 less you need each year lowers your FI number by $25,000 at a 4% rate and frees up money to save.

Revisit yearly. Update your balance and savings each year to see progress.

Use it for decisions, not just retirement. Knowing you're halfway to FI can make it easier to drop to 0.8 FTE or leave a job that isn't working.

Grow your savings faster with the backdoor Roth and 403(b) calculators, and see the effect of steady investing with the compound growth calculator.