Burn Rate, Runway, Default Alive: How Startups Should Track Cash

Burn rate and runway are the two most important numbers in any startup — and the two most often misreported. Clean tracking of both is non-negotiable for serious operating discipline and fundraising.

Burn rate

Gross burn rate: Total monthly cash outflow (salaries, rent, software, ads, cloud, legal, etc.).

Net burn rate: Gross burn minus monthly revenue.

Example:

• Monthly costs: $500K.
• Monthly revenue: $150K.
• Gross burn: $500K/month.
• Net burn: $350K/month.

Runway

Runway (in months) = Current cash balance / Net monthly burn.

Example:

• Cash: $6M.
• Net burn: $350K/month.
• Runway: ~17 months.

Default alive vs default dead

Paul Graham’s framework (2015 essay):

• Default alive: With current growth trajectory and no new funding, the startup reaches profitability before running out of cash.
• Default dead: Without new funding, the startup runs out of cash before reaching profitability.

How to compute default alive

1. Project revenue growth: Use realistic, not aspirational, growth rates.
2. Project cost growth: Usually lower than revenue growth (unit economics).
3. Extend forward until revenue covers costs.
4. Compare to current runway: If profitability arrives before cash runs out, you’re default alive.

2026 context

• Default alive is back in fashion: Post-2022, LPs and VCs reward disciplined capital efficiency.
• 24-month runway is now the default fundraise target (up from 18 months in 2020–2021).
• AI infrastructure burn: Companies with material compute spend need to model it separately.

How to extend runway

1. Reduce burn:
   • Headcount: the largest lever in most companies.
   • Cloud/compute: increasingly material for AI-heavy startups.
   • Marketing: cut lowest-ROI spend first.
2. Increase revenue:
   • Existing customers: expansion, upsell, price increases.
   • New customers: accelerate sales cycle; tighten close rates.
3. Raise capital:
   • Bridge or priced round.
   • Venture debt.
   • Revenue-based financing for capital-efficient companies.

Common reporting mistakes

1. Using gross burn when investors ask for net (or vice versa).
2. Ignoring seasonality: Q4 revenue bursts can mask Q1 weakness.
3. Excluding one-time costs: Tax payments, legal fees must be modeled.
4. Ignoring receivables timing: Billed revenue is not cash.

Practical takeaway

1. Founders: Track net burn and runway weekly; share monthly with board.
2. Investors: Push portfolio companies toward default alive; extend runway before financial pressure.
3. Operators: Build a 3-scenario forecast (pessimistic, base, optimistic) and refresh monthly.

Further reading

• Paul Graham’s “Default Alive or Default Dead?”: http://paulgraham.com/aord.html