Gross Margin vs Unit Economics

Definition

Gross margin is the percentage of revenue left after subtracting the direct costs of delivering your product (Cost of Goods Sold / COGS). For SaaS, COGS includes hosting, customer support, and payment processing — typically leaving 70-85% gross margins. For e-commerce, COGS includes product costs, shipping, and packaging — typically 30-50% margins. Gross margin determines how much money you have to invest in growth (sales, marketing, R&D). A SaaS company with 80% gross margins has $0.80 per revenue dollar for growth; a hardware company with 30% margins has only $0.30.

Common trap

The trap is miscategorizing expenses to inflate gross margin. Some companies exclude customer success, onboarding, or infrastructure costs from COGS to make gross margins look SaaS-like (75%+) when they're really services businesses (50-60%). VCs see through this immediately. If your 'SaaS' has 55% gross margins, you're not a SaaS company — you're a services company with a software wrapper. The valuation difference is 3-5x.

Practical use

Calculate gross margin honestly: include ALL costs directly related to delivering your product to one more customer. For SaaS: hosting/infrastructure, payment processing, customer support, DevOps. Formula: Gross Margin = (Revenue − COGS) ÷ Revenue × 100. Target: 70%+ for SaaS, 50%+ for marketplace, 30%+ for e-commerce. Track monthly and investigate any decline — it usually means infrastructure costs are scaling faster than revenue.

Formula

Definition

Unit economics is the direct revenue and costs associated with a single 'unit' of your business model (usually one customer). If your unit economics are positive, every new customer generates profit. If negative, every new customer accelerates your death. The core calculation: Unit Profit = (LTV × Gross Margin) − CAC. If LTV is $2,000, gross margin is 80%, and CAC is $1,200, unit profit is ($2,000 × 0.80) − $1,200 = $400 per customer. This means each customer eventually contributes $400 toward covering fixed costs and generating profit.

Common trap

Founders often achieve 'positive unit economics' by excluding fixed costs entirely or misclassifying variable costs. True unit economics must include a fair allocation of all variable costs. The second trap: assuming unit economics stay constant as you scale. They can improve (economies of scale in hosting, support) or worsen (higher CAC from market saturation, more support tickets from less-sophisticated users). Track unit economics by cohort and by scale.

Practical use

Calculate profit per unit: (LTV × Gross Margin) − CAC. If this number is negative, do NOT scale. Fix your pricing, reduce CAC, or improve retention first. Scaling negative unit economics is like pouring gasoline on a fire — you burn faster. Once positive, track the 'contribution margin ratio': Unit Profit ÷ Revenue per Customer. This tells you what percentage of each revenue dollar covers fixed costs.

Formula