Classifying Costs
Part 1: Direct vs Indirect, Fixed vs Variable
The three-dimensional cost classification framework every product leader needs — behavior, function, and traceability. Why the same cost can be fixed AND COGS, and why that matters for your financial model.
Part 2: A Laundry List of Examples for SaaS Costs
Where specific costs land in the P&L for cloud-native, ML/data-intensive B2B SaaS businesses. A reference guide for cloud compute, storage, data acquisition, ML work, people, and third-party services.
SaaS Finance
Part 1: Stating the Obvious
The financial characteristics of SaaS businesses that experienced operators take for granted but first-time founders and PMs need to internalize — compounding, churn, the J-curve, and operating leverage.
Part 2: The P&L Waterfall, Line by Line
A detailed walkthrough of each line in the SaaS P&L waterfall — Revenue through Net Income — with worked examples using fictional dev-tool products.
Part 3: Acronyms and Profitability Metrics
MRR, ARR, ACV, gross margin, contribution margin, EBIT, EBITDA, churn rate, and net revenue retention — what each means, how to compute it, and what good looks like.
Part 4: Rules of Thumb
The efficiency metrics and heuristics that investors use to evaluate SaaS businesses — Rule of 40, Magic Number, Burn Multiple, and the PE investor's checklist.
Unit Economics for Product Leaders
Part 1: Unit Economics Arithmetic
Core unit economics formulas for B2B SaaS — common errors in ARPU and LTV calculations, dimensional analysis, revenue-based vs. margin-based LTV, and the weighted LTV problem.
Part 2: The Bridge to the P&L
How per-customer unit economics connect to portfolio-level P&L, the cost taxonomy that matters, why gross margin ≠ contribution margin, and the explicit bridge from unit economics to profitability.
Part 3: Five Decision Frameworks
Product decision frameworks built on unit economics — the attribution trap, variable vs. fixed cost reduction, bundling economics, capacity-constrained optimization, and breakeven pricing floors.