Apple Inc. (NASDAQ:AAPL) has scheduled an event for tomorrow and is widely expected to show off the iPhone 6—probably two different sizes and potentially with two different names. Of course when it is unveiled tomorrow, there will be a lot of focus and dissection of the smartphone’s features, but that won’t be all analysts are scrutinizing. Stifel analysts said they will also be looking at expectations for build numbers and the implications of a new form factor on Apple’s gross margins.

Apple iPhone 6

Projecting iPhone 6 launch numbers

In a report dated Sept. 7, 2014, analysts Aaron Rakers, Joseph Quatrochi and Andrew Shinn said they are predicting that Apple will sell between 10 million and 13 million iPhone 6 units over launch weekend, topping last year’s record launch of 9 million iPhone 5S units. In 2012, Apple shipped more than 5 million iPhone 5 units. They note that in China last year, preorders started on Sept. 17.

Apple subscribers

iPhone 6’s impact on Apple’s gross margins

In terms of gross margins, the Stifel team reminds investors that Apple set a capital expenditures target of $11 billion for the 2014 fiscal year. Most of that amount was equipment, machinery and internal use software. They note that Apple will see a depreciation cycle of about three to five years, which means that depreciation and amortization expenses will accelerate, thus impacting the cost of goods sold and the gross margin percentage.

They say that Apple saw a comfortable gross margin of about 37%. However, they think investors will question that percentage and consider the iPhone 6 release as being more relative to that of the iPhone 5 because of the different form factor.

The analysts also remind investors, however, that Apple guided for about a 400 basis point sequential decline in gross margins for the December 2012 quarter but ended up beating it by about 260 basis points.

How many will upgrade to the iPhone 6?

The Stifel team also notes that a recent survey from comScore found that 35% of current iPhone owners in the U.S. said they are likely to upgrade to the iPhone 6 within the next six months. The firm found that iPhone 4 users had the highest likelihood of upgrading.

Apple iphone upgrade

The analysts at Stifel also note that the iPhone 6 is going up against Samsung Electronics Co., Ltd. (LON:BC94) (KRX:005930)’s newest offerings, the Galaxy Note 4 and the Galaxy Note Edge, which were just unveiled last week.

They add that when Apple finally shows off the iPhone 6, investors will be looking on the smartphones most important attributes. Some things investors will be looking for include the expected larger display, whether Apple ended up going with sapphire glass or Gorilla Glass for the display, and whether the rumored mobile payments system with near field communication is included. They think investors will also be looking for wireless charging.