Cash Runway is the number of months a business can continue to operate before it runs out of money, assuming its current revenue and spending levels remain constant. For startups that are not yet profitable, runway is the ultimate 'Survival Clock.' It is calculated by dividing the current cash balance by the average monthly 'Net Burn' (total spending minus total revenue). Understanding your runway is essential for strategic planning; it dictates when you need to raise your next round of capital, when you need to achieve profitability ('Default Alive'), or when you need to make difficult budget cuts to extend the business's life. A safe runway is typically 18-24 months, which allows 6 months for growth, 6 months for a fundraise, and a 6-month safety buffer. Founders must monitor runway religiously, as running out of cash is the #1 reason startups fail. Proactive runway management allows teams to focus on building rather than panic-fundraising in a position of weakness.