Apple is ordering a combined 70 to 80 million units of two big-screen versions of its next iPhone, its largest initial production to date, according to a report in The Wall Street Journal.
The company is anticipating large demand for the so-called iPhone 6 as it will be available with screens measuring 4.7 and 5.5 inches diagonally, the report said, citing unnamed sources.
The 70 to 80 million units by December 30 would be much more than the 50 to 60 million units last year for the iPhone 5S and 5C, which have 4-inch screens. The iPhone 4S has a 3.5-inch display.
Apple has asked component makers to get ready to turn out up to 120 million new iPhones by the end of the year to take into account a possible higher failure rate for displays, the report said.
Manufacturing the 5.5-inch screen could be tricky because of the complexity of integrating touch sensors into the LCD, it said, adding that using sapphire crystal instead of glass for the display would add to the difficulty.
The new screen size has been the subject of much speculation as displays have taken up more phone real estate in recent years.
Until 2011, 4 inches was the largest screen for most phones on the market, but it has become the minimum since 2013.
Apple rival Samsung posted an ad on YouTube on Monday that depicts an iPhone user with "screen envy" while ogling the Galaxy S5, which has a 5.1-inch screen.
Apple did not immediately respond to a request for comment on the report.