Startup Financial Basics: Budgeting, Runway, and Burn RateStartup Financial Basics: Budgeting, Runway, and Burn Rate
Financial literacy isn’t optional for founders, even those without a finance background. A handful of core concepts, tracked consistently, give you an early warning system for problems and a clear picture of how much time you have to hit your next milestone.
Burn Rate
Burn rate is how much cash your business spends per month beyond what it brings in. Gross burn is total monthly expenses; net burn subtracts revenue from that figure. Tracking net burn monthly, even in a simple spreadsheet, tells you immediately whether your spending is trending in a sustainable direction.
Runway
Runway is simply your current cash balance divided by your net burn rate, expressed in months. If you have $120,000 in the bank and are burning $15,000 a month, you have eight months of runway. This single number should inform nearly every spending decision, since running out of cash, not lack of profitability, is what actually ends most startups.
Build a Rolling Budget
Rather than a static annual budget, maintain a rolling 12-month cash flow projection that you update monthly with actual results. This keeps your runway estimate accurate and surfaces problems, like an unexpected expense or slower-than-planned revenue growth, while there’s still time to react.
Separate Personal and Business Finances Immediately
Mixing personal and business expenses, even informally, makes it nearly impossible to understand your real burn rate and creates headaches for taxes, fundraising due diligence, and legal protection. Open a separate business bank account as soon as you start spending or receiving money for the business.
Know Your Key Milestones
Runway matters most in context of what you need to accomplish before it runs out, whether that’s reaching a specific revenue target, hitting a product milestone that supports a fundraise, or reaching profitability. Work backward from that milestone to decide whether your current spending pace gives you enough time, and adjust early rather than waiting until the number looks alarming.