Burn rate: gross vs net

Burn rate is the speed at which your company consumes cash, and it comes in two forms. Gross burn is your total monthly operating spend; net burn is that spend minus the revenue you collected. Investors quote net, because net sets runway. This guide covers measuring both honestly, and reporting them so the numbers keep earning trust.

The two burn rates

Gross burn is everything the company spends in a normal operating month — payroll, contractors, infrastructure, rent, software. Net burn is that spend minus the revenue you actually collected: the amount your bank balance falls. A startup spending $50K a month while collecting $10K of revenue has $50K of gross burn and $40K of net burn.

They are not two precisions of the same number; they do different jobs. Gross burn measures commitment. It is what you’re on the hook for whether or not revenue shows up, and it is the floor your revenue eventually has to reach — the $50K company above is, among other things, claiming its revenue line can climb past $50K before the cash runs out. Read your own gross burn the way an investor does: as the size of the bet.

Net burn is survival math. It is the rate the account drains, the denominator in every runway calculation, and the number that decides how many more months of attempts you get. Two companies with identical $40K net burn sit at the same point on the survival clock even if one spends twice as much gross — the gross number is where their ambition and risk diverge; the net number is where their clocks agree.

Which burn investors quote

Net — because net is the number that sets runway. When an investor asks about burn, the question underneath is how long you can keep operating, and only net burn answers it: cash divided by net burn is the survival clock, and everything else in the conversation hangs off it. If gross and net ever blur together in your reporting, the runway math stops being checkable — which costs more trust than either number being high.

But experienced investors read gross too, and what they read in it is revenue quality. The gap between gross and net is exactly the revenue doing work against your cost structure — when net burn runs well below gross, revenue is carrying a real share of the load. When the two numbers sit nearly on top of each other, the company is still almost entirely investor-funded, whatever the narrative says. The $50K-gross, $40K-net company above has revenue covering a fifth of its spend: early, but visibly real work. Watch that gap over time — it is the cleanest single picture of a business learning to carry itself.

When the conversation moves from speed to efficiency — what the burning actually buys — the ratio investors reach for is burn multiple. But the default question, the one under every runway discussion, is answered by net.

Measuring burn honestly

There are two legitimate ways to measure burn, and the discipline is running both.

The expense-sum methodreads the P&L: add up the month’s operating outflows. It is precise about intent — it reflects the spending you decided on — and that is also its blind spot. Annual prepays land as a lump in one month, contractor invoices clear late, refunds wander in, and anything you forgot to book simply doesn’t exist. The expense-sum answer is what your burn was supposed to be.

The bank-delta methodskips intent and measures the account: take the balance three months ago, subtract today’s, divide by three. It cannot miss anything, because the account itself is the source of truth. Three months is the standard window — long enough to smooth one-time items into the average, short enough that the answer still describes the company you’re currently running.

When the two methods disagree by more than a rounding error, believe the bank — then go find the difference. That gap is usually the most useful output of the whole exercise: an annual renewal nobody remembered, revenue recognized but not collected, a category of spend living outside the books. The free burn rate calculator runs both methods side by side — no signup — and surfaces any disagreement in about a minute.

Presenting burn in the investor update

In the update, burn is one number: net, under a frozen definition, with its direction against last month. Not a table of expense categories, not gross and net and EBITDA in a row — one number the reader can compare to the one you sent last month. The sample company running through these guides reports it in six words:

Net burn $38,400, down $2.1k vs March.

Frozen definition means net burn this month is net burn every month — and if the definition ever has to change, the update says so in the same breath. Direction means the reader never computes the diff themselves. And when burn jumps, annotate the cause in the same sentence: a hire, a one-time legal bill, an annual prepay. “Net burn $47,300, up $8,900 — two engineers started mid-month” reads as control. The same number with no annotation reads as drift, or as something you hoped nobody would notice — and the reader can’t tell which.

Where the number sits in the format is covered in how to write an investor update, and what to include in an investor update covers the metrics that ride alongside it — burn is one of the four that appear in every monthly update, in the same order, every time.

Deliberate burn vs drift

The useful question about burn is rarely “how much” — it is “on purpose, or not?” Raising burn to chase a channel that is working is a decision: you can name what the added spend buys, when you expect it back, and what you’ll do if it stops working. Burn that rises because seats renewed, tools accumulated, and nobody re-examined the contractor retainer is drift. The amounts can be identical; the companies are not.

Drift resists detection because no single line item looks wrong. The catch is a quarterly line-item review: export every recurring charge, walk the list, and put each one to the question that separates deliberate burn from drift — what is this dollar of burn buying, and would you buy it again today? Spend that survives the question is strategy. Spend that survives only because nobody asked is drift, and most companies find some the first time they look.

When to cut

The signal worth respecting: runway under about nine months with no raise actually underway. That is not a panic line — it is the point where the time left stops being enough to both fix the number and run a fundraise on top of the fix. If you’re not sure where you stand, how to calculate startup runway walks through the honest version of the math, and the default-alive question — does current growth reach profitability before the cash runs out — tells you how much the clock should be dictating.

When the answer is cut, cutting early and once beats cutting late and twice. A single decisive cut resets the plan and lets everyone who stays get back to work; a series of small, late cuts spends the same cash and the morale twice over. Founders rarely regret the timing of an early cut — the common regret is having waited a quarter to believe the number.

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