With Apple due to report its fiscal Q3 (calendar Q2) earnings later today, Fortune notes that the company has beaten Wall Street expectations for eight straight quarters – and strong iPhone sales mean that today’s earnings report is likely to make it nine.

iPhone sales typically drop in June as consumers hear more rumors about the next model and many decide to wait. But with Q3 sales estimated at close to 50M phones, representing a massive 40% year-on-year increase, that would put Apple’s revenue well in excess of the company’s own guidance of $47B and above the Wall Street consensus estimate of $49.5B … 

While Apple gave extremely conservative guidance under Steve Jobs’ leadership, the real numbers almost always far higher, Tim Cook switched to giving guidance he believed to be as accurate as possible. Asymco’s Horace Dediu observed yesterday, though, that the company has exceeded the top end of its own guidance for the past three quarters.

While estimates of Apple Watch sales have been extremely variable, iPhone sales are far more significant, accounting for around 70% of Apple’s total earnings. It was recently reported that Apple takes 92% of the total profits for the entire smartphone industry, and the company has been promoting the iPhone in a series of “If it’s not an iPhone, it’s not an iPhone” ads.

For the first time in many years, I feel that there is some potential uncertainty in the results Apple will announce [on Tuesday]. After a period of excellent accuracy, the company’s guidance has begun to diverge dramatically from reality and the trend might continue this quarter.

We’ll of course be bringing you the actual Q3 numbers as soon as they are released, together with a live blog of the earnings call. Apple last quarter reported record second-quarter sales of both iPhone and Mac, together with all-time record earnings from the App Store.

Photo: AP Photo/Jeff Chiu