Runway Math That Doesn't Lie

Most founders calculate runway with last month's burn. That number is almost always wrong.

Use a 3-month trailing average

Last month was probably anomalous (a big invoice, a delayed hire, a one-off). Take the average of the last 3 months of net burn.

runway_months = cash_on_hand / avg_net_burn_last_3_months

Subtract the things you're pretending aren't happening

• That hire you're definitely making in 6 weeks
• The tools renewal you forgot about
• Taxes

Two numbers, not one

• Default-alive runway: what you have today.
• Plan runway: what you have if your next 90-day plan plays out.

If those two numbers diverge by more than 3 months, your plan is the fantasy.

The honesty checkpoint

Every month, write down the runway you reported last month and the runway you have now. If it drops faster than 1 month per month, you're burning faster than you think.

Money lies to founders who want it to. Math doesn't.