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The Founder's Marketing Math Handbook

CAC, LTV, payback period, contribution margin, runway. Attribution without the bullshit. ICP scoring math. The 4 marketing math mistakes every SMB founder makes. ~25 pages, framework-driven, with worked examples for SaaS / service / e-com.

Marketing25-page PDFPublished May 17, 2026

Most SMB founders are flying blind on marketing math. They know what CAC stands for. They cannot recall theirs from memory. They cite LTV figures based on customers they hope to keep, not customers they actually keep. They confuse contribution margin with gross margin and run unprofitable channels for months before noticing. This handbook hands you the 5 numbers every founder should know cold, the attribution rules that survive contact with reality, an ICP scoring matrix you can run on 100 leads in 20 minutes, and the 4 mistakes I see on every Activation Audit. Built for founders who don't have a finance background and don't have time to read a 300-page textbook. The math is high school. The opinions are the hard part.

What’s inside

The 5 numbers every founder should know cold: CAC, LTV, payback period, contribution margin, runway burn. Definitions, formulas, the founder mistakes for each, worked examples for SaaS / service / e-com.
Attribution without the bullshit: first-touch vs last-touch vs blended vs incremental. When multi-touch attribution is a vendor lie. The 3-channel rule.
ICP scoring math: the Fit + Intent + Reachability matrix. The 1-10 fit scale that actually works. How to score 100 leads in 20 minutes.
The 4 marketing math mistakes every SMB founder makes: counting MRR before churn, LTV over a lifetime you can't predict, confusing margin with revenue, ignoring blended payback.
A one-page quick-ref cheat sheet at the back: every formula, every threshold, every yes/no test. Print it. Pin it. Stop guessing.

Frequently asked

How math-heavy is this? I don't have a finance background.

Multiplication and division. No calculus, no statistics theory. Every formula is presented as a plain-English sentence first, then as the formula. The hard part isn't the math; it's deciding which numbers to track and which to ignore. The handbook spends more pages on that than on the arithmetic.

Will this work for SaaS / services / e-commerce / agency?

All four. Each section includes worked examples for SaaS (subscription revenue, churn, expansion), services (project margins, retainer math), and e-commerce (AOV, repeat rate, contribution per order). Agency math is a hybrid; the service section covers it.

Why no MQL / SQL / SAL definitions?

Funnel-stage definitions are downstream of the math. If you don't know your CAC or contribution margin, your MQL definition doesn't matter. This handbook covers the upstream numbers. If you want the funnel-stage math, read this first, then add lead-scoring on top using our ICP scoring chapter as the underlying framework.

Is this just the textbook formulas I can find in Lenny's Newsletter / Reforge?

The formulas are textbook because the math is textbook. The opinions are not. Most marketing math content presents the formulas and stops. This handbook tells you which inputs to refuse (LTV beyond 18 months is fiction for most SMBs), which models to never deploy (multi-touch attribution for businesses under $5M), and which numbers to track even though every vendor will tell you they don't matter (contribution margin per channel).

When should I re-read this?

Every time you raise prices, change channels, hire someone whose comp depends on a marketing metric, or look at an end-of-quarter dashboard. The math doesn't change. Your application of it does. We update the handbook annually based on what shows up wrong on Activation Audits in the previous year.

Stop reading. Ship something.

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Frequently asked

How math-heavy is this? I don't have a finance background.

Will this work for SaaS / services / e-commerce / agency?

Why no MQL / SQL / SAL definitions?

Is this just the textbook formulas I can find in Lenny's Newsletter / Reforge?

When should I re-read this?