If you have raised any outside funding — or are planning to — there are two financial metrics that matter more than almost anything else in the early stage: burn rate and runway. Investors ask about them. Your board tracks them. And ignoring them is one of the fastest ways to run your startup into the ground.
Here is a plain-English breakdown of both concepts, how to calculate them, and what you can actually do about them.
What Is Burn Rate?
Burn rate is how much cash your startup spends each month beyond what it brings in. It is a measure of how quickly you are going through your capital reserves.
There are two versions:
Gross burn is your total monthly expenses — everything you spend, regardless of revenue. If you spend $80,000 per month on salaries, software, rent, and marketing, your gross burn is $80,000.
Net burn is your monthly cash loss after accounting for revenue. If you spend $80,000 but bring in $30,000 in revenue, your net burn is $50,000. Net burn is typically the more important number because it reflects your actual cash consumption.
Understanding your burn rate is foundational to understanding your cash flow — and cash flow is what keeps a startup alive month to month, regardless of how promising the business looks on paper.
What Is Runway?
Runway is how many months your startup can survive at its current burn rate before running out of cash.
The formula is simple:
Runway (months) = Cash on Hand ÷ Monthly Net Burn
If you have $600,000 in the bank and your net burn is $50,000 per month, you have 12 months of runway.
Runway is critical because fundraising takes time — often 3 to 6 months from first meeting to money in the bank. Most experienced operators recommend never letting your runway drop below 6 months before actively fundraising. Waiting until you have 3 months left puts you in a deeply unfavorable negotiating position.
Why Clean Books Are Essential for Tracking These Numbers
You cannot calculate your burn rate accurately if your books are a mess. Burn rate depends on knowing exactly what you spent last month — which requires properly categorized, reconciled financial records.
This is one of the core reasons why accurate monthly bookkeeping matters so much for funded startups. When your monthly financial reports are delivered on time each month, you always know your current burn rate and can update your runway projection immediately after each close.
Founders who rely on rough estimates or outdated spreadsheets routinely underestimate their burn — and get caught off guard. According to the Small Business Administration, poor cash flow management is one of the leading causes of small business failure.
How to Calculate Your Burn Rate and Runway
Step 1: Pull Your Monthly P&L
Your Profit & Loss statement for the most recent month shows your total expenses (gross burn) and your revenue. Subtract revenue from expenses to get your net burn.
Step 2: Average the Last 3 Months
A single month can be distorted by one-time expenses. Use a 3-month average of your net burn for a more reliable baseline.
Step 3: Check Your Current Cash Balance
Log into your business bank account and note your current balance. If you have multiple accounts, include all business cash — operating account, savings, any short-term investments.
Step 4: Divide Cash by Monthly Net Burn
That is your runway in months. Update this number every single month when your books close.
How to Extend Your Runway
When runway is shrinking and a fundraise is not imminent, you have two levers: reduce burn or increase revenue. Here are the most common tactics on the expense side:
Audit your software subscriptions. Growing startups accumulate SaaS subscriptions quickly. Many are underused or redundant. A monthly expense review often surfaces $2,000 to $5,000 per month in tools that can be cancelled or downgraded without impacting operations.
Delay non-essential hires. Payroll is almost always the largest line item on a startup P&L. Before adding a full-time employee, consider whether a contractor or part-time hire can meet the immediate need while preserving runway.
Renegotiate vendor contracts. Annual commitments negotiated at a higher revenue stage may have renewal clauses. Many vendors — especially software companies — will discount to retain a customer.
Accelerate collections. If you invoice customers on net-30 or net-60 terms, consider offering a small early payment discount (1–2%) to accelerate cash inflows. Faster collections directly reduce net burn without touching your cost structure.
What Investors Want to See
When you raise your next round, investors will ask for your burn rate and runway as part of standard diligence. They want to see that you know your numbers cold — and that you have a clear plan for how the new capital extends runway to the next milestone.
Be prepared to present your last 3 months of actuals and a 12-month forward projection. Both depend entirely on having clean, accurate books. If your financials are not investor-ready, our team can help. Schedule a free consultation and we will get your books in shape before your next raise.