After wrapping up 2017 with expectation-crushing fourth-quarter results, streaming-TV company Netflix (NFLX 1.34%) officially crushed it last year. Not only did the stock soar 55% during the year, but it jumped 10% after the company reported on its fourth quarter in January.

There was a lot to love about Netflix in 2017. Helped by its 24 million new members during the year, profits skyrocketed 191% and international streaming revenue rose 58% compared to 2016. Can Netflix's momentum continue in 2018? We're about to find out.

A poster displaying various Netflix Originals movies

Image source: Netflix.

Ahead of Netflix's first-quarter earnings report on Monday, here's a preview of five key metrics to watch.

1. Streaming revenue

After fourth-quarter results came in well above its own guidance for the period, management was optimistic about Q1. This optimism is particularly evident in Netflix's guidance for streaming revenue. The company said it expects total first-quarter streaming revenue of about $3.6 billion, up about 43% year over year compared to its streaming revenue of $2.5 billion in the year-ago period. If Netflix achieves this growth in streaming revenue, its year-over-year growth in the key metric would be up significantly from the 35% growth it saw in Q4. 

2. International streaming revenue

Netflix's international streaming revenue was particularly strong in Q4, rising 64% year over year. Looking to Q1, management guided for even faster year-over-year growth of 70%.

What's notable about the guidance for streaming revenue in Q1 is that it's very close to management's expectations for U.S. streaming revenue, highlighting how international streaming revenue could soon exceed domestic revenue. Indeed, if international streaming revenue comes in better than expected in Q1, it could surpass U.S. streaming revenue in during the period. Netflix guided for first-quarter international streaming revenue of $1.78 billion and U.S. streaming revenue of $1.81 billion.

3. International contribution margin

As international streaming revenue has climbed, so too has profitability. In Netflix's fourth quarter, its international streaming contribution margin (revenue less cost of revenue and marketing expenses incurred by the segment as a percentage of segment revenue) was 8.7%, up from negative 7% in the fourth quarter of 2017. The big jump in Netflix's international contribution margin during the quarter helped the company report its first full-year contribution profit for the segment last year.

Management expects an even stronger international streaming contribution margin in Q1, guiding for a margin of 13.1%.

4. Operating margin

Management has been able to easily justify its big spending on content since it has been benefiting from undeniable operating leverage, evidenced by Netflix's outsize growth in profitability during 2017. To check on its continued progress in scaling its business and improving its operations, investors should check on Netflix's operating margin. After all, even management calls its operating margin its "primary profit metric." 

In 2017, operating margin was 7.2%, but management aniticpates its full-year operating margin to land at 10% in 2018.

5. Streaming members

Finally, investors should look for more strong growth in Netflix's streaming members. After all, if the company is going to live up to its stock's pricey valuation, it needs to continue adding members even as competition intensifies.

Netflix guided for 6.35 million new streaming members, or a total of 124 million members, during Q1. Though these net member additions would be lower than the 8.33 million added in Q4, it's significantly higher than the 4.95 million members added in the first quarter of 2017.

First-quarter results for Netflix will be posted after market close on Monday, April 16.