Apple Inc. said many customers will need to wait until next month for their new iPhones after a record 4 million first-day pre-orders were logged, double the number for the iPhone 5 two years ago.
The company said demand had outstripped supply of the new iPhone 6 and iPhone 6 Plus, which feature larger screens and longer battery life. Deliveries of pre-orders will begin on Friday and will continue through October.
Bumper first-day pre-orders point to first-weekend sales of up to 10 million units, analysts estimated.
"Assuming preorders are similar to the 40 percent of first weekend sales for the iPhone 5, this would imply iPhone 6/6Plus first weekend sales could be around 10 million," Wells Fargo Securities analysts wrote in a note.
About 2 million pre-orders were received for the iPhone 5 in the first 24 hours after it went on sale in September 2012. Apple sold 5 million of these phones in the first weekend.
Apple sold 9 million iPhone 5Ss and 5Cs, which were launched last year, in the first three days in stores. The company did not reveal pre-order numbers for these phones.
Raymond James analysts said they expect sales of iPhone 6 and iPhone 6 Plus to top 9 million in the first weekend.
"Apple will be selling every iPhone it can make, at least through October. Because of this, the first weekend sales are typically more indicative of supply than demand," they said.
The company routinely grapples with iPhone supply constraints, particularly in years that involve a smartphone re-design.
Apple's website showed last week that the larger 5.5-inch "Plus" models displayed a wait time of up to a month. The 4.7-inch version was available for delivery on Sept. 19.
Janney Capital Markets analysts said the large number of pre-orders was due to "pent-up demand" for bigger iPhone screens.
The brokerage raised its sales estimate for the latest iPhones to 37.4 million units for the current quarter and 60 million for the quarter ended December.
"We believe significant demand will even spill into the March and June quarters given supply and the timing of shipments in China," Barclays analysts wrote in a note.
The company said the new iPhone models will be available to customers in its stores in the United States, Canada, Australia and some other countries on Friday morning.
AT&T Inc, Sprint Corp, T-Mobile US Inc, Verizon Wireless and some Apple authorized resellers will also start selling the phones on Friday.
The phones will come equipped with Apple's new payments service, "Apple Pay," which launches in the United States next month and allows users to pay for items in stores with their phones.
Apple's shares were up less than 1 percent at $102.92 Monday afternoon.