The math everyone learns
Runway = cash on hand ÷ monthly burn. A $500K seed at $50K/mo burn = 10 months. That number is what investors track. It's also the number founders most often miscalculate by underestimating burn.
What founders underestimate
Common burn-rate omissions:
- Founder salary (some founders forget to count their own)
- Contractor fees and one-time legal
- SaaS subscription creep — Stripe, Vercel, Postgres, Sentry, Resend, Linear, Notion, etc. easily $1K/month
- The 25% on top of every salary for benefits + payroll tax
- The $5–10K legal bill that shows up on a 90-day cycle
What changed in 2026
A 2022-era seed-stage runway calculation assumed one to two engineering hires eating $250K–$400K of year-one budget each. In 2026 the same scope ships with one senior engineer on AI-native workflow — see AI-native engineering and flat-price engagement.
The implication: a $500K seed now buys you 18–24 months instead of 10–12, if you actually shift to the new model. Founders still hiring at 2022 prices burn at 2022 rates.
The right runway target
Most VC playbooks say 18 months of runway is the safety zone. We'd say 24 months for pre-PMF teams. The faster you can extend runway without hurting the team's velocity, the higher your survival odds — and ship-fast engineering is the single biggest lever after team size.
