Apple (AAPL) is scheduled to report its Q3 2018 earnings after the bell on Tuesday, with analysts expecting to see $2.15 earnings per share on revenue of $52.31 billion.

The most closely watched number, though, will be the amount of iPhones sold during the previous three months. That gives investors a look into whether consumers are still interested in the current generation of iPhone. Analysts expect Apple to have sold 41.3 million handsets in the quarter. That would be a slight year-over-year increase from Q3 2017, when it sold 41 million.

Beyond iPhone sales, smart investors will be on the lookout for the average selling price of each handset. A higher ASP means that more consumers purchased the expensive iPhone 8 Plus and iPhone X versus the base iPhone 8. And since the iPhone 8 Plus and iPhone X offer better profit margins than the 8, a greater number sold means more money in Apple’s coffers. This year, analysts are expecting an ASP $699 compared to $607 for the same quarter last year.

For those trying to suss out Apple’s future beyond the iPhone, the most important number to watch will be services revenue. Services include Apple Music, iTunes and iCloud and, if they continue to grow, could make for more stable earnings for the company in the long term.

Services revenue is estimated to be $9.23 billion, compared to $7.2 billion for the same quarter last year.

We’ll have updated coverage of Apple’s earnings when they become available.

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