We tend to talk about social networks in terms of size, because audience reach is one of social media’s biggest advantages. That’s why Facebook gets so much attention. With 1.2 billion monthly active users, it’s a beast.

But as audiences adopt newer social networks, and people’s social activity becomes increasingly fragmented, other measures of social network activity become more important, especially for businesses trying to determine where to best allocate time and resources. How much time users spend on each social network and how engaged and interactive they are with content there are increasingly important ways of evaluating the sites.

In a new report, BI Intelligence calculates an Engagement Index for top major social networks and compares their performance in terms of time-spend terms per-user, on desktop and mobile. We also look at how the different top activities on social media -- photo-sharing, status updates, etc. -- are indexing in terms of activity, and which sites drive the highest volume in each category. This report complements our popular reports on social media demographics and global audience sizes

Access The Full Reports And Data By Signing Up For A Free Trial Today >>

Here are our findings:

1. Social is now the top Internet activity. Americans spend an average of 37 minutes daily on social media, a higher time-spend than any other major Internet activity, including email.

2. Social-mobile rules. 60% or so of social media time is spent not on desktop computers but on smartphones and tablets. 

3. Facebook has a monster lead in engagement. Facebook is a terrific absorber of audiences' time and attention, 114 billion minutes a month in the U.S. alone, on desktop PCs and smartphones. By comparison, Instagram commands 8 billion minutes a month, and Twitter just 5.3 billion. 

4. Facebook attracts roughly seven times the engagement that Twitter does, when looking at both smartphone and PC usage, in per-user terms

5. Snapchat is a smaller network than WhatsApp, but outpaces it in terms of time-spend per user

6. Pinterest, Tumblr and LinkedIn have made major successful pushes in 2013 to increase engagement on their mobile sites and apps. The new race in social media is not for audience per se, but for multi-device engagement. 

7. Multi-device social media. Our analysis is based on BI Intelligence's social media Engagement Index, which compares the effectiveness of social networks in keeping individual users engaged across smartphones and desktop PCs (for an explanation of the Index, sign up for instant access to BI Intelligence). 

Here are our PC-smartphone Engagement Index scores for five platforms:

  1. Facebook, 50.7
  2. Instagram, 13.5
  3. Twitter, 7.4
  4. Snapchat, 6.6
  5. WhatsApp, 4.6

The report is full of charts and data that can be easily downloaded and put to use

In full, the report:

For full access to the report on Social Engagement sign up for a free trial subscription today.

This article originally appeared on Business Insider.