Gross Margin | Investing Glossary

What it is

Gross margin is what remains of revenue after subtracting the direct cost of making or delivering the product. For a manufacturer, that's materials, labour, and factory costs. For a retailer, it's the wholesale cost of the goods it sells. For a SaaS company, it's server costs and customer support for existing users.

It is the first line of the income statement after revenue and the most fundamental test of whether a business model is intrinsically attractive.

How to calculate it

**Gross Margin = (Revenue − Cost of Goods Sold) ÷ Revenue × 100**

The key is knowing what "cost of goods sold" (COGS) includes in each industry. For a software company, COGS includes cloud hosting and support staff but not salespeople or engineers building new features. For a pub group, COGS includes alcohol and food but not rent and managers' salaries. Always understand what's in the line before comparing across companies.

What it tells you about the business model

Gross margin is the single number most predictive of long-term business quality. A high gross margin means the company captures significant value from each unit it sells, leaving plenty of room to fund sales, marketing, R&D, and management before reaching the operating profit line.

Low gross margin businesses are not inherently inferior — supermarkets run on 25% gross margins and generate enormous absolute profits through scale. But they have little room for error and must manage costs and volume with precision. A 3% improvement in cost of goods for Tesco can have a dramatic effect on operating profit. A 3% swing in COGS for AstraZeneca barely moves the needle.

Gross margin as a moat indicator

Warren Buffett has noted that companies with consistently high gross margins are often those with genuine competitive moats — either pricing power (customers will pay premium prices) or cost advantages (they produce more efficiently than competitors).

Look at Reckitt Benckiser: health and hygiene brands like Dettol and Durex enable 60%+ gross margins because brand recognition allows premium pricing and customers are relatively price-insensitive on products they trust. Compare that to a generic FMCG supplier with no brand differentiation, operating at 20% gross margins. The structural difference in competitive position is stark.

UK gross margin leaders (approximate):

Pharmaceuticals: 65–80% (AstraZeneca, GSK)
Software / tech: 65–85% (Sage, Kainos)
Premium beverages: 55–65% (Diageo, Fever-Tree)
Consumer healthcare: 50–65% (Reckitt, Haleon)
Aerospace components: 30–45% (Rolls-Royce, Melrose)
Grocery retail: 22–28% (Tesco, Sainsbury's)
Construction: 15–25%

Margin erosion: the danger signal

A gross margin that has been falling for several years is often the first sign of a deteriorating competitive position. It might mean:

Competitors are undercutting on price and the company is being forced to respond
Input cost inflation is eating into the margin and cannot be passed on to customers
A shift in product mix toward lower-margin offerings

Conversely, gross margin expansion — even modest, consistent improvement over several years — suggests a strengthening competitive position and is a positive indicator for operating profit growth to follow.

**Analyst's shortcut:** Run the gross margin over five years. If it's stable or improving, the business model is likely sound. If it's drifting down, understand exactly why before buying. Gross margin compression that management cannot clearly explain is a red flag.

Not financial advice. Gross margin analysis should always be considered alongside absolute revenue scale and business context.