Instagram has 700m monthly active users

"Instagram has doubled its user base, to 700 million monthly actives in two years, fueled by Stories, web signups and better onboarding on low-end Android phones. Instagram’s growth rate is actually speeding up. It took just four months to add the last 100 million users since hitting 600 million in December, while it took six months to go from 500 million to 600 million.
Here’s a breakdown of how long it took Instagram to add each 100 million users:
October 6, 2010 – Launch
February 26, 2013 – 100 million;  28 months
March 25, 2014 – 200 million; 13 months
December 10, 2014 – 300 million; 9 months
September 22, 2015 – 400 million; 9 months
June 21, 2016 – 500 million; 9 months
December 15, 2016 – 600 million; 6 months
April 26, 2017 – 700 million; 4 months
For reference, this makes Instagram more than twice the size of Twitter. Soon it might join Facebook’s other properties in the billion-user club, since WhatsApp and Messenger have 1.2 billion users and Facebook 1.8 billion."

Source:  Techcrunch, 26th April 2017