Apple (AAPL 1.66%) will announce the results for its important holiday quarter on Jan. 31, according to an updated schedule on the company's website. Investors will undoubtedly be watching the update closely. Apple's fiscal first quarter of 2017, ending Dec. 31, marked the first full quarter of iPhone 7 and 7 Plus availability. Will the new iPhone help Apple return to revenue growth?

Ahead of the earnings release, here's an early look at some of the key metrics worth looking into.

iPhone 7. Image source: Apple.


Apple's fiscal 2016 marked a rare year-over-year decline in revenue for the company. Sales during the fiscal year were about $217 billion, down about 8% from Apple's record $234 billion in revenue during fiscal 2015. The company's inability to grow its top line has suppressed the stock's valuation as investors wonder if Apple can grow from here. Apple stock currently has a price-to-earnings ratio of just 14 -- wildly low for an established market leader as dominant as Apple.

Still, some investors may be hoping Apple can either turn revenue around during fiscal 2017 -- or at least put a stop to top-line declines. Investor hope for a return to growth is actually encouraged by Apple management; the company guided for fiscal 2017 first-quarter revenue between $76 and $78 billion, representing a slight uptick from Apple's $75.9 billion of revenue in the year-ago quarter.

Investors may be hoping Samsung's recall of its Note 7 during the holiday quarter will serve as a catalyst for Apple's September-launched iPhone 7 and 7 Plus. With Samsung's flagship smartphones clearly standing out as the biggest competition to Apple's iPhones -- especially in the U.S. -- the Note 7's recall should have helped drive some incremental iPhone sales during the quarter. And since iPhone accounts for about 60% of Apple's total revenue, a solid quarter for iPhone should make a return to growth more likely.

Earnings per share

Another key area to watch will be Apple's earnings per share. But investors shouldn't expect the metric to return to growth the way revenue could. Even if revenue turns upward, Apple is expecting a lower gross profit margin in its first quarter than it sported in the year-ago quarter; a lower gross profit margin on only a slight uptick in revenue would likely mean EPS for the quarter will still be lower than in the year-ago quarter.

Apple store. Image source: The Motley Fool.

Apple said it's expecting a gross profit margin between 38% and 38.5% for its first quarter. In the year-ago quarter, Apple's gross profit margin was 40.1%.

Importantly, as investors digest the quarter's results, investors should keep in mind that even if Apple's EPS declines on a year-over-year basis because of a narrower gross profit margin, worsening profitability will likely mostly be attributable to factors unrelated to Apple's regular operations. In the year-ago quarter, Apple's gross profit margin benefited from a $548 million award for patent infringement. Further, Apple's guidance for a 38% to 38.5% first-quarter gross profit margin takes into account expectations for 60 to 70 basis points of currency headwinds.

Whatever EPS Apple reports, it would likely be worth investors' time to look for an explanation from management about what factors drove EPS higher or lower (probably lower) during the quarter.

For a reference point, the consensus analyst estimates for Apple's revenue and EPS during the quarter are $77.4 billion and $3.22, respectively. This would compare to revenue and EPS of $75.9 billion and $3.28, respectively, in the year-ago quarter.

Apple will release its first-quarter financial results after market close on Jan. 31. The results will be available on the tech giant's investor relations website. Stay tuned at The Motley Fool for more Apple coverage leading up to earnings, as well as a Foolish look at Apple's first-quarter results after they're released.