How Gross Margin Is Calculated for a B2B SaaS Business

SaaS gross margin is calculated by subtracting the cost of goods sold from total revenue and dividing the result by total revenue. For a SaaS business, cost of goods sold includes only the direct costs of delivering the product: hosting infrastructure, third party API costs, and the portion of customer support directly attributable to product delivery. No other costs belong in this calculation.

The Distinction That Matters

Gross margin is not a percentage. It is a business model verdict. The number reveals whether the product itself is economically viable before any growth spending occurs. A SaaS business with 75% gross margin has £0.75 of every revenue pound available to fund growth, operations, and eventual profitability. A business with 40% gross margin is structurally constrained — it cannot reach the unit economics that institutional investors expect from software without fundamentally changing its cost of delivery. The gross margin line is where investors form their first opinion about whether the model scales.

What distorts this figure most commonly is the misclassification of costs. Salaries for the customer success team, product engineering salaries, and marketing technology costs are operating expenses, not cost of goods sold. Including them in the gross margin calculation understates the true margin and produces a figure that will not survive a first round of financial diligence.

Why It Surfaces in a Raise Process

In a Series A process, investors calculate gross margin independently from the financial model before the first detailed conversation. They compare it to sector benchmarks: SaaS businesses at scale typically carry 70% to 85% gross margin; businesses below 60% face questions about delivery model efficiency. A company that presents a 68% gross margin derived from a correctly classified cost structure stands in a different position from one that presents 68% by accidentally excluding support headcount costs that belong in cost of goods sold.

The Common Structural Error

The most common error is mixing operating expenses into cost of goods sold to make the gross margin calculation appear more complete. This typically occurs when founders build the income statement without separating cost of goods sold from operating expenses in the chart of accounts from the start. A chart of accounts built without this structural separation cannot produce a credible gross margin figure and requires reconstruction before any investor review.

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Tool: Startup Financial Readiness Scorecard