Hootsuite and We Are Social publish an annual report detailing internet use and social media growth. In their 2018 report, they list the most active social platforms (slide 59), led by Facebook (2,167B MAUs), with WeChat at #5 (980M MAUs). Because Facebook is still not used in China (not broadly), we have added the Facebook and WeChat user figures to roughly approximate the number of people using social media. At 3.147B, this comes very close to the report’s estimate of active social media users (3.196B).

src:
We Are Social/Hootsuite, Jan 2018
“2018 Global Digital”
full set of slides

I tallied historic MAU data from Facebook (Q3 2008 – Q4 2017) and WeChat (Q2 2011 – Q2 2017)

src:
Facebook via Statista, Jan 2018
“Number of monthly active Facebook users worldwide as of 4th quarter 2017 (in millions)”

src:
Tencent via Statista, Aug 2017
“Number of monthly active WeChat users from 2nd quarter 2010 to 2nd quarter 2017 (in millions)”

I calculated this tally as a percentage of global population, to be compared against the percent of global internet users (reported by the Internet Telecommunications Union).

global population src:
United Nations, Department of Economic and Social Affairs, Population Division. World Population Prospects: The 2017 Revision. (Medium-fertility variant).
via Worldometers

I used Excel to create trend lines (2deg polynomial) showing when each set (internet users and social media users) might reach 100% saturation.

The data are collected in the following Excel file:
global-internet-users-ITU-2001-2017-extrap-to-2030

And a simplified Google Drawing is here:
https://docs.google.com/drawings/d/1qbYyLORAMPYAtwZkrZxN0-VTfjUpPLoZL-SV-z-IB9E/edit?usp=sharing

Other bits of interest:

Dragon Social, Oct 2017
“10 Most Popular Social Media Sites in China”

eMarketer, June 2017
“Percent of Internet users who use a social network at least 1x/month”
2016-2021

Business Insider, Sep 2016
“Messaging apps are now bigger than social networks”
[crossing chart]
2011-2017

ASK: Forecasts for global 100% internet users?

FINDINGS:

eMarketer publishes a ~5-year forecast of internet penetration every year. It’s most recent publicly accessible forecast showed a downward revision from the previous year’s forecast.

As of June 2016
2014 41.1%
2015 44.3%
2016 46.8%
2017 49.0%
2018 51.1%
2019 53.0%
2020 54.6%

src: eMarketer, June 2016

Revised, as of April 2017
2016 44.6%
2017 46.8%
2018 48.8%
2019 50.6%
2020 52.2%
2021 53.6%

src: eMarketer, April 2017

This is the only significant forecast I’ve found for this indicator.

*

The International Telecommunications Union tracks internet users as a percentage of the global population. Historic data is available back to the mid 1990s.

I’ve added a trendline projection, which suggests ~2030 as a possible saturation date.

However, when eMarketer’s most recent forecast figures are added, the trendline wiggles. The same type of trendline (2nd order polynomial) then delays saturation until 2040.

Adjusting the trendline type (to a 5th order polynomial) gives a better R-squared value, and again brings saturation back to ~2030.

[Black and yellow simplified chart here]

src:
International Telecommunications Union, 2017
“Global ICT developments, 2001-2017*” [XLS file]

Here’s a tidy chart, showing data points, of basically the same data (1997-2017) aggregated at Wikipedia, with separate lines for global, developed world, and developing world:

src: Wikipedia citing Internet Telecommunications Union

*

Newsweek projection of when the number of active Facebook users will equal the current (2017) population of the world (7.6B) — 2048

Newsweek’s fine print: The forecast has been calculated only using the annual figures provided by Facebook’s reports since 2004, and does not take into consideration technological progress or demographic changes.

CC’s NOTE: In 2048, the UN medium fertility variant projection for world population is 9.7 billion. At 7.6 billion users, that would be about 78% of the projected 2048 population. That would be a big jump from the 26% of global population FB users accounted for in 2017, but still not literally everyone.

src:
Newsweek, May 2017
“How Long Until Facebook Takes Over The World?”