Consider the new device that Apple launched on Monday. No, not the one on Tim Cook’s wrist — the new MacBook. A decade ago, Apple’s personal computers were at risk of being overshadowed by their Windows rivals, but in recent years Macs have been a steady source of revenue growth. Mac revenues were $25bn in the past 12 months — watch sales this year will come nowhere close, even by the rosiest projections. It would take, say, 60m watches a year to get there.

As a peek inside a university classroom confirms, Apple has gained ground in PCs. The market as a whole shrank last year in units shipped, while Mac unit sales rose 16 per cent. Apple computers are now the fifth most-shipped PCs globally, according to IDC, a forecaster. Meanwhile the average selling price of the Mac has held firm, falling only 3 per cent in the last three years. And Mac demand will benefit as Apple further integrates the software on its computer, tablets and phones.

But there is a catch. When Macs comprised 15 per cent of Apple’s revenues, they were just 7 per cent of gross profits, according to a Credit Suisse analysis last year. The gross margin, of about 20 per cent, is far below the company average, which was 40 per cent last quarter. It is the iPhone, of course, that generates most of the profits. Analyst estimates put the iPhone gross margin at 45 per cent or more. The iPhone has dramatically increased Apple’s gross margins over the past decade (unlike virtually every other hardware company in the world).

The watch will probably have very high margins, too. This is easy for the fanciest versions, which range from $10,000 to $17,000. JPMorgan estimates the cost of materials for the top-end model is about $800. Even the entry-level watches, which start at $350, have a gross margin of about 45 per cent, JPM thinks. So a mere 27m watches a year (or so) produces Mac-level profits. Too bad MacBooks do not come in 18-carat gold — yet.

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