The FU Number
Track months of runway; anything past six is the freedom to experiment with your life.
- Difficulty
- Easy
- Time to result
- ~months to results
- Steps
- 4
- Confidence
- 80%
Sam Parr's personal-finance framework is to track your runway — months you could live with zero income — and treat everything above six months as your 'FU number,' the cushion that buys freedom to experiment, change direction, or chase a passion. The discipline is to keep expenses low and ruthlessly grow the cushion even on a modest income, because the real trap is the opposite: people who spend right up to (or above) what they earn, so a missed bonus puts them underwater. He's seen seven-figure earners with $0 in savings. Irreversible expense burdens — lifestyle creep, a Hamptons place, college debt — are what quietly remove the flexibility to take the very risks that lead to fulfillment.
Origin
Sam Parr built a spreadsheet tracking saved cash against burn (using an app called My Weekly Budget), defining anything beyond six months of runway as his FU number and freedom to experiment.
Core principles
- 01Runway equals freedom; measure it in months.
- 02Above six months is your FU number.
- 03Keep expenses low and grow the cushion ruthlessly.
- 04Spending up to your income is the real trap.
- 05Irreversible expense burdens steal your flexibility.
How to run it
- 1
Measure your runway
Track cash saved and divide by monthly burn to know how many months you could live with no income.
- 2
Set the six-month threshold
Treat everything beyond six months of runway as your FU number — the flexibility to experiment or walk away.
- 3
Keep expenses low
Live frugally and grow the cushion ruthlessly even on a modest income, rather than letting spending rise with earnings.
Pro tip Sam grew his number aggressively while not making much money, purely through low expenses.
- 4
Avoid irreversible burdens
Steer clear of lifestyle creep, status purchases, and debt that lock your expenses at the top of your income.
Watch out College debt and running your budget to the top can trap you in a job and remove all flexibility.
In the wild
Sam used the My Weekly Budget app and a spreadsheet to track saved cash as 'how long you could live without income,' defining anything above six months as his FU number and a license to experiment.
→ A concrete, ruthlessly-grown cushion that funded the freedom to take risks.
Gurley describes New York peers on decent entry-level pay who got a Hamptons place and a private club, running their budgets to (or above) the top, so a missed bonus put them underwater; Sam notes million-a-year earners with $0 saved.
→ High income without a cushion left them with no flexibility and no FU number.
Common mistakes
Spending up to your income
Letting expenses rise to meet earnings means a single missed bonus leaves you underwater and trapped in your job.
Taking on irreversible burdens
Debt and fixed status costs remove the flexibility to take the risks that lead to fulfillment.
Is it for you?
Best for
Anyone who wants the financial flexibility to change jobs, take risks, or chase a passion.
Not ideal for
People with no discretionary income at all, for whom the first task is raising income, not saving.
From the transcript
“Anything above 6 months, that's like your FU number. Meaning you could go and try and experiment.”
“I know people that make seven figures a year, $1 million a year, and will literally have $0 in savings.”
From the episode
Bill Gurley: 6 Out of 10 People Are Making This Mistake
Bill Gurley