A startup has $6 million in the bank. Every month it spends half a million more than it earns.
That monthly gap has a name. It is called the burn rate.
What Burn Rate Is
Burn rate is how much cash a company loses each month.
From Burn to Runway
Divide the cash by the burn. $6 million, at half a million a month, is 12 months.
That number is the runway. On this publication’s arithmetic from those two figures, the cash falls by half a million each month, to $3 million at month 6 and to nothing at month 12.
At half a million a month, $6 million lasts 12 months. The in-between figures are this publication’s subtraction. Round numbers for illustration.
The Idea on One Board
Round numbers From Burn to Runway
$6 millionat half a million a monthis 12 months
Three Ways Out
Before the runway ends, the company must do one of three things. Earn more. Spend less. Or raise more money.
Burn at an AI Company
For AI companies, the burn is often the computing bill, and it grows as customers arrive.
So each new customer can shorten the runway, because the computing bill rises with them.
Why It Matters
The video turns this into one question: how many months of cash are left, at today’s burn?
Burn rate is how fast the cash goes. Runway is how long until it is gone.
The key insight: Burn rate is how fast the cash goes. Runway is how long until it is gone.
The honest limit
For AI companies, the burn is often the computing bill, and it grows as customers arrive.
So each new customer can shorten the runway, because the computing bill rises with them.
Our report on Reflection’s SpaceX compute deal says that CNBC reported that Reflection agreed to pay SpaceX $150 million a month from 1 July 2026 through 2029, with either side able to exit on 90 days’ notice after the first three months. Axios, CNBC and Bloomberg are the sources, and we verified none of it independently. How fast cash goes out each month is the subject of this lesson.
The Business Engineer Lens
Where this idea sits in the Business Engineer library:
The Business Engineer framework maps where each part of the AI stack sits and who holds the leverage. These pills are short lessons from the same library.
Burn Rate builds on Free Cash Flow. Burn is cash lost each month; free cash flow shows cash brought in minus spending on buildings and equipment.
Inference drives the cost of Burn Rate. For AI companies the burn is often the computing bill, and it grows as customers arrive.
Financial Conditions constrains Burn Rate. Raising more money is one way out of burn, and financial conditions set how easy and costly that borrowing is.
Take-or-Pay(lesson unlocks soon) drives the cost of Burn Rate. A fixed chip bill keeps arriving when demand slows, and the burn lesson says AI burn is often the computing bill.
Primary and Secondary(lesson unlocks soon) constrains Burn Rate. Only primary money goes into the company, so only it extends the runway that burn shortens.
Gennaro Cuofano is a CRO and tech executive who has worked in AI since late 2015, starting with bringing NLP, natural-language generation, voice and chatbot products to the marketing industry. His background is in law and finance: he holds a Master's degree in Law and an International MBA with an emphasis on corporate finance (LUISS Business School and the University of San Diego, 2012), and worked as a financial analyst at a real-estate investment firm in San Diego and as an assistant controller. His work focuses on business model strategy, business engineering and, more broadly, structural analysis: how companies make money, read from their own filings. He created FourWeekMBA and leads research there and at The Business Engineer, his newsletter on AI and business strategy, with over 95,000 subscribers and more than 1,000 published analyses. His writing has also appeared on Entrepreneur (for example, How to Digitize a Family Business in Europe) and HackerNoon. Find him on LinkedIn and Substack. See how we source.
