Tech-giant Apple (AAPL -0.35%) will report earnings after market close today. As the most valuable company in the world, the tech giant is bound to make some noise. Given the way stocks have kicked off 2022, investors are likely crossing their fingers that the iPhone-maker has a good earnings report up its sleeve.

While it's difficult to gauge where revenue and earnings will fall for the quarter, one thing is certain: The company entered the quarter up against a tough year-ago comparison and some serious supply constraints, which explains why analysts have largely muted expectations for the period.

iPhone 13 Pro Max in four different colors.

iPhone 13 Pro Max. Image source: Apple.

What Apple reported one year ago

On Jan. 27, 2021, Apple reported an exceptional first quarter of fiscal 2021. Revenue for the period rose 21% year over year as earnings per share increased 35%, hitting a record high. Revenue for the period was $111.4 billion and earnings per share was $1.68. 

The tech-company's momentum was broad-based, with double-digit year-over-year revenue growth across every product category and record revenue in each of the company's geographic segments. iPhone sales, which accounted for 59% of the period's revenue, were a major driver of the quarter's performance. iPhone revenue increased from about $56 billion in the first quarter of fiscal 2020 to close to $66 billion in the first quarter of fiscal 2021.

Demand for the iPhone 12 family of smartphones was "very strong despite COVID-19 and social distancing measures, which have impacted store operations in a significant manner," said Apple CFO Luca Maestri in the year-ago earnings call. The product-segment's momentum pushed Apple's installed base of actively used iPhones past 1 billion for the first time.

What to expect from Apple's most recent quarter

It's safe to say that such a strong year-ago quarter translates to a bit of a headwind for Apple in its first quarter of fiscal 2022. Put simply: The quarter is a tough comp.

But this isn't Apple's only challenge in its first quarter of fiscal 2022. Management also said in its most recent earnings call that it expects the supply constraints it faced last quarter to persist in fiscal Q1. In fact, Apple said it expects the negative impact from supply constraints to be larger in fiscal Q1 than it was in the prior quarter, when constraints led to an estimated $6 billion of lost revenue for the period.

Within this context, analysts' conservative view for the period may start to make sense. Analysts are currently modeling for revenue to increase just 5% year over year. This would be a significant slowdown from the 29% year-over-year quarterly revenue growth Apple posted three months ago.

But actual revenue for the first quarter of fiscal 2022 could be very different from analysts' forecasts. There are a handful of uncertain factors making this a wildcard quarter. For instance, Apple could have solved some of its supply constraints earlier than expected. On the other hand, supply constraints for the quarter could have been worse than anticipated. And it's worth pondering: Is demand for the latest iPhone models sufficient enough for the important product to see meaningful sales growth on top of a tough year-ago comparison?

Tune into Apple's fiscal first-quarter earnings report after market close today to see whether or not revenue slowed as much as expected.