Runway Calculation: The Number Every Founder

Runway Calculation for Startups

Every founder can quote their runway. Few can defend the assumptions behind it. When runway falls under 12 months, investors ask about your assumptions — not the headline number.

The formula

Runway (months) = Cash on hand / Net monthly burn. Net burn = gross spend − revenue. Cash on hand should exclude committed-but-unused (like SAFEs not yet closed) and receivables not yet paid.

Three runway scenarios to model

Base case: current burn, current growth. Bear case: burn holds, growth stalls (no new revenue). Bull case: expansion revenue and pipeline conversion play out. Investors want to see all three, with the assumptions documented.

The trap of "gross runway"

Some founders quote runway assuming zero revenue drops. That's misleading. Real runway assumes revenue holds only if churn is stable. Model both revenue-holding-flat and revenue-declining scenarios.

When to trigger fundraise

Start fundraise conversations at 15-18 months of runway. Formal raise at 12-15 months. Under 6 months you're in a distressed raise and will accept bad terms. Do not let runway drop below 6 months without a signed term sheet.

Frequently asked questions

What counts as "cash on hand"?

Money already wired to your bank. Not signed SAFEs. Not committed credit lines. Not receivables. Investors will haircut anything else.

Should we model runway to profitability?

For a Series A pitch, yes. Path-to-default is a red flag. Show what needs to be true to reach cash-flow neutral before running out.

How to extend runway without cutting people?

Renegotiate vendor contracts. Move to annual pricing from monthly. Accelerate collections. Convert some full-time roles to contract. Cut ads with unclear payback. People-cuts are the last lever, not the first.

Related fundraising guides (40)

• Startup Runway Guide
• Runway Calculator
• Runway Extension
• Runway Planning
• Burn Rate vs Runway
• SaaS Metrics
• SaaS Valuation Calculator
• SAFE vs Convertible Note
• SAFE vs Priced Round
• SAFE vs Priced Round Calculator
• Sales Capacity Model
• Sales Commission Plans
• Sales Compensation
• Sales Efficiency
• Sales Enablement
• Sales Forecasting
• Sales Methodology
• Sales Motion
• Sales Pitch
• Sales Playbook
• Sales Tax Compliance
• Sales Velocity
• Scenario Planning
• SCIM Provisioning
• SDR Playbook
• Search Infrastructure
• Search Relevance
• SEC Filings
• Secondary Sale
• Secondary Sale Guide
• Secondary Shares
• Secondary Transaction
• Secrets Management
• Security Questionnaires
• Seed Round
• Seed vs Series A
• Self-Serve Motion
• SEO Strategy
• Series A
• Series A Checklist

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