SAN FRANCISCO: Instagram, the photo and video-sharing service owned by Facebook, now has almost 5m more smartphone users in the US than Twitter, the latest estimates from eMarketer have revealed.

Its analysis found that 34.6m Americans accessed Instagram at least once a month in 2013, representing growth of 34.7% since 2012, compared with 30.8m who used Twitter's mobile app.

Although Twitter continued to attract a slightly higher proportion of total internet users – 17.6% compared to Instagram's 16.1% – the findings confirmed that it is lagging behind Instagram among smartphone users.

Twitter's adoption among smartphone users is projected to grow modestly from 21.3% in 2013 to just over a quarter (25.7%) of US smartphone owners in 2018, although this will represent a near doubling of actual users from 30.8m in 2013 to 56.5m in four years' time.

Twitter is also expected to maintain an older demographic than Instagram, which is particularly popular among millennial and Generation X users.

Over three-quarters (69%) of Instagram's users were aged between 18 and 44 in 2013 and eMarketer did not expect significant change in usage by age for either site until 2018.

In a separate demographic finding, eMarketer reported that women still accounted for the majority of Instagram users, but increasing adoption among men will take the gender ratio down to 55% women versus 45% men by 2016.

Coming in the same week that Facebook founder Mark Zuckerberg announced that Instagram had achieved 200m monthly active users around the world, eMarketer analyst Deborah Aho-Williamson told the Financial Times that the platform was coming on "very rapidly".

She said advertisers regarded it as a "beautiful branding platform" to highlight images and videos, although she didn't think advertisers would desert Twitter.

"The use cases are so different. Instagram is so much about sharing photos and video and little graphics whereas Twitter is so much more real-time information and news," she said.

Data sourced from eMarketer, Financial Times; additional content by Warc staff