The Anatomy of Burn Rate: What Most Startups Get Wrong

Burn rate is the most cited metric in startup finance — and one of the most misunderstood.

The Gross vs Net Confusion

Most founders report *gross burn*: total cash out the door each month. But the number that actually determines survival is *net burn* — the difference between what leaves and what comes in. A company spending $120K/month with $80K MRR has a net burn of $40K, not $120K. The distinction sounds obvious until you're in a board meeting quoting the wrong figure.

The Three Layers of Burn

A useful burn model separates spend into three categories:

1. Fixed infrastructure — rent, tooling, committed contracts. These are inertial. They don't change next month regardless of what you decide today. 2. Team burn — salaries, benefits, employer taxes. This is usually 65–75% of total spend and the only lever with meaningful size. 3. Variable growth spend — paid acquisition, events, contractors. The first thing to cut, the last thing to regret cutting.

When investors ask about burn, they want to understand which of these three levers is driving the number and which are controllable on short notice.

The Runway Calculation Nobody Does Right

Runway = Cash / Net Burn. Simple. But what cash? Most founders use current bank balance. The correct input is *accessible* cash: bank balance minus committed future obligations (next payroll, annual contracts due, tax liabilities). The gap between those two numbers is often 15–25% of the balance.

Building a Burn Dashboard That Works

A working burn dashboard has four cells: - This month's net burn (actual) - Rolling 3-month average net burn (trend) - Projected runway at current burn - Projected runway at +20% burn (stress scenario)

The second row is what most teams skip. Trend matters more than point-in-time because it tells you whether the situation is improving or deteriorating — before the bank balance confirms it.

When to Raise vs When to Cut

The decision to raise or cut is fundamentally a question about your burn trajectory. If net burn is falling month-over-month and runway exceeds 14 months, you're in a position to raise from strength. If burn is flat or rising and runway is under 10 months, cutting is not optional — it's the precondition for any fundraise succeeding.

LedgerOS surfaces this signal automatically, flagging when the trailing burn trend crosses a configurable threshold so the conversation happens before the crisis does.