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Cash & runway

Burn rate and runway calculator

Enter your cash, spend, and collections to get gross burn, net burn, and the month your cash runs out.

Parag Jain, CPA
Parag Jain, CPAFounder, Zinance·Last updated August 2026·7 min read
Summarize this article
Measure runway against
Runway on net burn10.0 monthsCash reaches zero around June 2027 if nothing changes. Start raising by December 2026.
Gross burn
$180,000 / mo
Net burn
$120,000 / mo
Default-alive at 18 months needs
$66,667 / mo net burn
Months of cover
10.0
Zero-cash date
June 2027
Start raising by (6 mo lead)
December 2026

An estimate based on a flat monthly burn. Real runway moves with hiring, seasonality, and collections.

Burn rate is how much cash leaves the business each month. Runway is how long the cash you hold will last at that rate. Together they set the real deadline on everything else: when you must start raising, how fast you can hire, and whether you negotiate your next round from strength or from need.

Gross burn versus net burn

Gross burn is total cash out — payroll, vendors, rent, tooling. Net burn is gross burn minus the cash you collect. Runway is measured against net burn, because that is what is actually draining the balance.

Why both matter

Net burn tells you how long you have. Gross burn tells you how exposed you are if revenue stops. A company with $200k gross burn and $190k net burn is in a very different position from one at $200k gross and $20k net, even though only the second looks comfortable on a runway chart.

Use collections, not bookings

The most common error in a runway model is using revenue booked rather than cash collected. A signed annual contract that invoices quarterly does not put a year of cash in the bank. If your customers pay on 30- or 60-day terms, your cash-in line should lag your revenue line by that much.

How much runway is enough

Common seed to Series A guidance is 12 to 18 months after a raise. Eighteen months gives roughly twelve months to hit the milestones for the next round and six months to run the process, which typically takes three to six months from first meeting to money in the bank.

What each runway band means in practice
Under 6< 6 mo
6 to 126-12 mo
12 to 1812-18 mo
Over 1818+ mo

Bands reflect common seed to Series A investor guidance, not a rule.

  • Under 6 months — raising from a weak position, or cutting. Start now.
  • 6 to 12 months — begin the raise. You have time to run a process, not to wait.
  • 12 to 18 months — the healthy band after a round.
  • Over 18 months — comfortable, and worth asking whether you are underinvesting.

Burn multiple: the quality question

Runway tells you how long you have. It says nothing about whether the money is buying anything. Burn multiple — net burn divided by net new ARR — is the number that answers that, and it is increasingly what investors grade on.

If your books are not current enough to trust these numbers, that is the problem to fix first. Our bookkeeping service keeps them current daily.

Frequently asked questions

What is the difference between burn rate and net burn?+
Burn rate is often used loosely to mean either. Gross burn is total cash out. Net burn is cash out minus cash in. When someone asks for your burn, they almost always mean net burn, but it is worth stating which you are quoting.
Should runway include money I have been promised but not received?+
No. Runway is measured against cash you actually control. A signed term sheet is not cash, and rounds fall through. Model it separately as a scenario rather than folding it into the base case.
What if we are profitable some months and not others?+
Use a trailing three-month average rather than a single month, and note the seasonality separately. A single good month can hide a trend, and a single bad one can start a panic that the average would not justify.
How often should I recalculate?+
Monthly, as part of the close. Burn moves whenever you hire, sign a vendor, or change collection terms, and a runway number that is three months stale has usually moved by more than you would guess.
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Numbers you can actually trust

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