Burn Rate and Runway: How Long Can Your Business Survive?

Burn rate is how much cash your business spends each month. Runway is how many months you can keep going at that rate. Together, they answer the most important question any business owner faces: how long do you have before the money runs out?

If you do not know these two numbers, you are flying blind. Here is how to calculate both and what to do with the answers.

Burn Rate: The Formula

There are two versions.

Gross Burn Rate = Total Monthly Operating Expenses

This includes everything: rent, salaries, software, marketing, insurance, utilities. Every dollar that leaves the business each month, regardless of revenue.

Net Burn Rate = Monthly Operating Expenses - Monthly Revenue

This is the more useful number. It tells you how much cash you are actually losing each month after accounting for income. If you spend $25,000 and earn $18,000, your net burn rate is $7,000. You are losing $7,000 per month.

If your net burn rate is negative (meaning revenue exceeds expenses), congratulations: you are profitable. But keep reading, because modeling what happens if revenue drops is still critical.

Runway: The Formula

Runway (Months) = Cash Reserves / Net Monthly Burn Rate

Cash reserves means cash in the bank. Not receivables. Not credit lines. Actual cash available today.

Example: You have $70,000 in the bank. Monthly revenue is $20,000. Monthly expenses are $28,000. Net burn rate is $8,000. Runway = $70,000 / $8,000 = 8.75 months. At current rates, you run out of cash in just under 9 months.

What Your Runway Number Means

12+ months: You have room to invest, test, and hire. Use this stability wisely, but do not become complacent. Burn rate can creep up faster than you expect.

6 to 12 months: Monitor closely. Focus on your core revenue drivers. Be cautious with new hires, major purchases, or growth experiments. Tighten spending on anything that is not directly generating revenue.

3 to 6 months: Contingency planning mode. Cut low-ROI spending immediately. Accelerate sales cycles. Consider short-term financing. Every decision should be evaluated through the lens of extending runway.

Under 3 months: Crisis mode. Take urgent action. Raise cash quickly through accelerated collections, bridge loans, or emergency cost cuts. Pause all new initiatives. Focus exclusively on survival.

Why Both Numbers Matter

Burn rate without runway tells you the speed but not the distance. Knowing you spend $25,000/month is useful. Knowing you have 4 months of cash left is actionable.

Runway without burn rate tells you the distance but not what is driving it. If your runway is shrinking, burn rate tells you whether the problem is rising costs, falling revenue, or both.

Track both monthly. Plot them on a chart. The trend matters more than any single month's number. If burn rate is increasing while revenue is flat, the runway line is curving downward. Act before it gets to crisis levels.

How to Extend Your Runway

1. Reduce monthly burn rate. Every $1,000 saved adds days or weeks to your runway. Trim non-essential spending: unused software subscriptions, excessive ad spend, contractors who are not generating clear ROI. Move from fixed costs (salaries) to variable costs (contractors) where possible.

2. Increase short-term revenue. Launch a quick offer. Promote an existing service. Bundle products for a limited-time price. Even one or two new clients can significantly reduce net burn rate and extend runway by months.

3. Collect payments faster. Shorten invoice terms. Enforce late payment policies. Request deposits on new work. Many businesses run out of cash while waiting to get paid, even though they are profitable on paper.

4. Renegotiate payment schedules. Talk to your landlord, your vendors, your software providers. Even a 30-day extension on your payables extends your runway without affecting your operations.

5. Delay capital investments. If you were planning to buy equipment, upgrade your office, or invest in a major software build, defer it. Lease instead of buying. Phase the investment over time instead of paying upfront.

For Profitable Businesses Too

If your business is profitable, your net burn rate is negative and your runway is technically infinite at current rates. But model the downside scenario. What happens if your biggest client churns? What if revenue drops 20% for three months? What if a major expense hits unexpectedly?

Calculate runway under each scenario. If losing one client puts you at 3 months of runway, you have a concentration risk problem that needs attention now, not after the client leaves.

The Monthly Review Cadence

Set a recurring calendar reminder on the first business day of every month. Pull your bank balance. Calculate your net burn rate from last month's actual numbers. Divide to get updated runway. Plot it on a simple spreadsheet or chart.

If your runway is increasing month over month, you are building stability. If it is decreasing, you need to act. The trend matters more than any single month's number. A temporary dip because of a one-time expense is different from a sustained decline because of rising costs or falling revenue.

Do not wait until you feel cash pressure to start tracking. By the time you feel it, you may already be in the 3-to-6-month danger zone. Start tracking now, while you have time to make calm, strategic decisions instead of panicked ones.

If you want help building a cash flow forecast that models these scenarios, book a call. Runway planning is the most underrated financial exercise a business owner can do.

Next step: see it in your free Instant CFO Snapshot.