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Burn Rate Calculator

Calculate your monthly net burn rate from cash at the start and end of a period — plus the runway that remaining cash buys.

Cash at start of period

Cash at end of period

Months in period

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How it works

Monthly net burn = (cash at start − cash at end) ÷ months · Implied runway = cash at end ÷ monthly net burn

Net burn rate is how much cash a business consumes each month after counting any revenue it brings in — the fall in the cash balance over a period, divided by the number of months. It is the single most important number for an unprofitable startup, because it sets how long the company can operate before it runs out of money. Dividing the cash you have left by the monthly burn gives runway, the months until zero. If the balance grew over the period, net burn is negative — the business is cash-flow positive and adding to its reserves rather than depleting them.

Worked example

A startup that began a 4-month period with $500,000 and ended with $420,000 burned 500,000 − 420,000 = $80,000, or $20,000 a month. The $420,000 remaining, divided by $20,000, buys about 21 months of runway at that pace.

Frequently asked questions

What is the difference between gross and net burn?

Gross burn is your total monthly cash outflow — all operating costs before any revenue. Net burn subtracts the cash revenue you bring in, so it reflects the actual monthly drop in your bank balance. This calculator measures net burn from the change in your cash position, which already nets out revenue.

What is a healthy burn rate?

There is no universal figure — it depends on how much cash you hold and how fast you are growing. The metric that matters is runway: many investors like to see at least 12–18 months of cash at the current burn, giving time to hit milestones or raise again before the money runs out.

How do I extend my runway?

Cut burn (reduce spend, delay hires, trim non-essential costs) or grow cash inflow (raise revenue or new funding). Because runway is cash divided by burn, a given dollar cut to monthly burn extends runway more the less cash you have left.

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Calculate how many months of runway your cash buys at your current monthly burn — and the approximate month your cash runs out.

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Calculate EBITDA from net income, interest, taxes, depreciation and amortization — plus the EBITDA margin against revenue.

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Calculate customer acquisition cost (CAC) from sales and marketing spend, and check the LTV:CAC ratio that tells you if growth pays.

Educational estimate, not financial advice.