What is Cost Structure in a Lean Canvas?

Definition

Cost Structure lists fixed costs like rent and salaries plus variable costs like delivery and fees, determining what you spend to run your business and survive.

Why it matters

Most early-stage founders massively underestimate costs. They forget to include their own time at market rate, payment processor fees (Stripe takes 2.9% + 30c), cloud costs that scale with usage, and the real cost of customer support. A SaaS startup charging 20 USD/month with a 12 USD/month cost to serve - including support, hosting, and fraud losses - has an 8 USD gross margin and no path to profitability. Knowing this on the canvas, not after burning 100,000 USD, is the point of writing it down.

How it applies

An AI tool that generates business plans has these cost lines: (1) Anthropic API at 0.12 USD per plan, (2) Mailgun email delivery at 0.001 USD per email, (3) AWS S3 + CloudFront at ~60 USD/month flat, (4) Stripe fees at 2.9% of revenue, (5) founder time at 15 hours/week assigned to 40 USD/hour opportunity cost. Now the founder knows that a free plan costs her 0.13 USD plus 2 cents of opportunity cost, and a paid plan at 20 USD nets 19.30 USD minus Stripe fees. That math drives every decision about freemium limits.

Common mistakes

• Leaving out founder time - if you bill 0 PLN/hour for yourself, you are lying about margins.
• Ignoring refunds, chargebacks, and fraud - these are real costs in any payment business.
• Forgetting customer support scales with users - a 1,000-user SaaS has a support cost line.
• Treating "marketing" as one line instead of breaking out paid ads, content, and tools separately.