Managing Cash Runway as a Bootstrapped Teen Founder

Cash kills more teen startups than bad products do. If you're bootstrapping with part-time job money or a small angel check, knowing exactly how many months you have left is non-negotiable.

• Track cash-in, cash-out, and bank balance every Friday — spreadsheet or Digits
• Runway = cash on hand ÷ net monthly burn (not gross spending)
• Under 6 months: start cutting or raising. Under 3: emergency mode
• Separate fixed costs (infra, tools) from variable (ads, inference) — cut variable first
• Keep a personal-vs-business firewall: never use the company card for pizza

Most teen founders under-count their burn because they forget about annual subscriptions and parental 'loans.' Write every dollar down, even the awkward ones.

# Runway cheat sheet

Cash on hand:        $8,400
Monthly revenue:     $1,200 (MRR)
Monthly costs:
  Hosting/infra      $180
  AI API             $340
  Tools (Linear...)  $90
  Part-time help     $600
  Total              $1,210

Net burn: $1,210 - $1,200 = $10/mo
Runway:   essentially infinite IF MRR holds

Stress test: MRR drops 30% -> burn = $370/mo -> runway = 22 months

Good looks like knowing your runway to the week, never being surprised by a bill, and hitting 'default alive' — where MRR covers burn — before your savings run out.