Startup Burn Rate and Runway: How Long Your Cash Lasts

Gross burn vs net burn

Gross burn is everything you spend in a month — salaries, rent, software, marketing, the lot. Net burn subtracts the cash you bring in, so it shows how fast your bank balance actually falls. A team with $80,000 of monthly costs and $30,000 of revenue has an $80,000 gross burn but only a $50,000 net burn. Runway is always built on net burn, because incoming cash genuinely extends how long you can operate.

Watch both numbers. Gross burn tells you how heavy your cost base is regardless of sales, which matters if revenue is volatile. Net burn tells you the real drain on the account this month. When founders say a company is "burning $50,000 a month", they almost always mean net burn.

Turning burn into runway

Runway is one division: cash in the bank divided by net monthly burn. With $600,000 in the bank and a $50,000 net burn, you have 12 months. That single number frames every big decision — when to raise, whether to hire, how aggressively to spend on growth. A team with three months of runway lives in a very different world from one with eighteen.

Because most startups fund-raise on a timeline, a common rule is to start raising when you have six to nine months of runway left, since a round can take months to close. If runway drops below that, the priority shifts sharply toward cutting burn or accelerating revenue rather than opening new bets.

Keeping burn honest month to month

Burn is not static. A new hire, a marketing push or an annual software renewal can lift it overnight, while a strong sales month can shrink net burn or even flip it positive. Recalculate every month from actual bank movements, not a plan made at the start of the year, so the runway you quote to your board and yourself is real.

A calculator makes this a two-minute ritual: enter cash on hand, monthly spend and monthly income, and read net burn and runway together. Doing it consistently turns cash from a source of dread into a number you steer by.

Frequently asked questions

What is a healthy burn rate for a startup?

There is no universal figure — it depends on your stage and how much runway it buys. A useful frame is runway, not the raw burn: many investors like to see at least 12 to 18 months of runway after a raise. A high burn is fine if it is funding real growth and you have the cash to cover it; the danger is high burn with short runway.

How do I calculate net burn rate?

Take your total cash spent in the month and subtract the cash you actually received. If you spent $80,000 and collected $30,000, your net burn is $50,000. Use cash actually in and out of the bank, not accrued revenue or invoices you have not yet been paid for, so the number reflects your real bank balance.

Does raising more money reduce my burn rate?

No. Raising money adds to your cash balance, which extends runway, but it does not change how fast you spend. Burn rate only falls when you cut costs or grow revenue. Fresh funding buys time; it does not fix an underlying burn that is too high for the revenue you generate.

How often should I check burn rate and runway?

Monthly at a minimum, right after you close the books. Fast-moving or low-runway startups often check weekly. The point is to catch a rising burn or a revenue dip early, while you still have months to react, rather than discovering a short runway when it is nearly gone.