iPhone unit sales: Why Gartner and IDC disagree

IDC used one number. Gartner used another. I asked why. This morning I got an answer.

On July 31, Apple announced that it had sold 41.300 million iPhones in the June quarter.

IDC published its June quarter iPhone estimates later that day; Gartner nearly a month later.

• IDC: 41.3 million
• Gartner: 44.7151 million

It wasn’t hard to guess where IDC got its estimate. I suspected I knew where Gartner got its number, but I asked just to be sure. This morning I got an answer:

Difference in the numbers between what Apple reported vs what we published is due to different type of numbers being compared. We publish device sales to end user (sell-out) in our market share report while Apple reports sales to channel (sell-in) during quarterly financial reporting.

That almost explains it. During the earnings call CFO Luca Maestri mentioned that iPhone channel inventory was reduced by 3.5 million during the quarter. Subtract 3.5 million from Gartner’s 44.7151 million and you get 41.2151 million. Why that’s less than 41.3 million is not explained. Nor where Gartner got all those significant digits.

Below: Three spreadsheets (click to enlarge).

From Apple 7/31/2018

From Gartner via Patently Apple 8/28/2018:

From IDC via VentureBeat 7/31/2018:

My take: It’s probably worth mentioning that none of Apple’s competitors share their unit sales numbers. Gartner and IDC cobbled together the rest of their numbers from who knows where.