What Is Burn Rate?

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Burn rate gets described a lot of ways — “how fast you’re losing money,” “your monthly cash outflow” — and most of those descriptions are close enough to be useful and vague enough to cause problems.

Let’s be precise about it, because the precision matters more than it seems like it should. Burn rate is the rate at which your company spends cash, measured monthly. There are two versions, and conflating them is where most confusion starts.

Here’s the distinction that actually matters.

1. Gross Burn

Your total monthly cash spend — payroll, rent, tools, contractors, everything going out the door. It doesn’t account for any money coming in.

2. Net Burn

Gross burn minus the cash you’re bringing in from revenue. If you spend $60,000 a month and collect $15,000 in revenue, your net burn is $45,000. This is the number that actually determines how long your cash lasts, because it reflects your real, net cash position each month.

Here’s why the distinction matters practically: two companies can have identical gross burn and wildly different runways, because one has revenue offsetting its spend and the other doesn’t. If you only ever look at gross burn, you’re missing the number that tells you when you’ll actually run out of money.

That said, gross burn isn’t useless — it’s the number that tells you how efficiently you’re spending, independent of revenue. Watching gross burn creep up quarter over quarter, even while revenue also grows, is a legitimate signal to look at where the spend is actually going and whether it’s buying you proportional growth.

A few things worth knowing about how burn rate actually behaves in a real company. It’s rarely flat. Burn tends to step up around hiring waves, and step down (temporarily) around cost-cutting decisions or delayed vendor payments. This is why I’d always look at a trailing three-month average rather than any single month — a single data point can mislead you in either direction.

It should also be compared to something. Burn rate on its own is just a number. Burn rate relative to your runway, relative to your growth rate, relative to your fundraising timeline — that’s where it becomes a decision-making tool instead of a statistic you report and move past. And it’s a lever, not a fixed cost of doing business. Every dollar of burn is a decision — a hire, a tool subscription, an office lease — and most of those decisions are reversible faster than founders assume, especially in the first eighteen months.

Bottom Line

Track both gross and net burn monthly. Use net burn to calculate runway, because that’s the number tied to your actual survival timeline. Use gross burn to sanity-check spending efficiency as you scale. The companies that get into real trouble aren’t usually the ones with high burn — they’re the ones who didn’t know their burn had changed until the bank balance told them.

Want a clear read on your gross and net burn?

8cast helps founders track burn accurately and turn it into a real planning tool. Get in touch to learn more.

Need help understanding your burn rate? 8cast supports founders from tracking to strategy. Reach out.