Definition of Runway
Runway refers to the amount of time a company can continue operating at its current spending rate before exhausting its available cash. It is expressed in months and is calculated by dividing the company's current cash reserves by its monthly net burn rate. Runway is a critical metric for startups and growth-stage companies because it determines how long the business has to reach the next milestone, whether that is profitability, a new revenue target, or the closing of the next funding round.
How Runway Is Calculated
Runway is calculated as: Runway (months) = Current Cash Balance / Monthly Net Burn Rate. For example, if a company has $3,000,000 in the bank and is burning $300,000 per month more than it earns, it has 10 months of runway. This calculation assumes the burn rate remains constant, which is rarely the case in practice. A more sophisticated model accounts for expected revenue growth, seasonality, planned hiring, and other changes to the cost and revenue trajectory.
Net Burn Rate vs. Gross Burn Rate
Burn rate comes in two forms. Gross burn is the total cash spent each month across all expenses. Net burn is gross burn minus revenue collected. A company with $500,000 in monthly expenses but $200,000 in monthly cash collections has a net burn of $300,000. Runway calculations typically use net burn because it reflects the actual cash depletion rate, accounting for revenue coming in.
Runway Explained for a General Audience
Runway is essentially a countdown clock. If a company has 12 months of runway, it has 12 months to either start generating enough revenue to sustain itself or raise more money before the bank account hits zero. Longer runway gives a company more time and flexibility to iterate, grow, and close a funding round without pressure. Short runway creates urgency that can force suboptimal decisions, such as raising capital at poor valuations or cutting costs that harm growth.
Why Runway Matters
Runway determines how much time a company has to execute its plan. With more runway, a company can take a measured approach to growth, attract better investors, negotiate from a position of strength, and avoid desperate decisions. Companies with short runway often must prioritize near-term survival over long-term strategy. Investors closely monitor runway because it signals financial discipline and the likelihood that a company will survive long enough to reach its goals.
Extending Runway
Companies can extend runway in two primary ways: reducing burn or increasing cash. Reducing burn involves cutting costs, slowing hiring, or deprioritizing lower-ROI initiatives. Increasing cash involves raising equity, taking on debt, or accessing non-dilutive financing such as revenue-based financing. A third lever is accelerating revenue collection: for example, incentivizing customers to pay annually upfront rather than monthly, which brings future cash forward without raising external capital.
Runway and Fundraising Strategy
Experienced operators typically begin fundraising at least 6 to 9 months before their runway would expire. This gives enough time to run a proper process, accept the best terms rather than the fastest terms, and accommodate the 3 to 6 months that institutional fundraising rounds typically require from first conversation to close. Running a fundraise with only 2 to 3 months of runway left puts the company in a weak negotiating position and increases the risk of failing to close in time.
Summary
Runway measures how long a company can survive at its current burn rate. It is one of the most important metrics for growth-stage companies because it governs how much time is available to execute the plan, reach milestones, and secure the next source of capital. Managing runway proactively by monitoring burn, accelerating revenue, and planning fundraises well in advance is a foundational responsibility of startup leadership and finance teams.
