Instagram grows to 500 million users as it flies past Twitter but is still dwarfed by parent Facebook

The site has grown fast – doubling its size in the last two years

An employee holds a cup with the Instagram logo at Facebook's corporate headquarters during a media event (Getty Images)

Instagram is now bigger than almost every country in the world, with more than 500 million people using it.

The site is growing fast, having doubled its size over the last two years. The site had just 400 million users in September.

That means that it has quickly dwarfed most of its rivals. Twitter, for instance, has seen its numbers of users get stuck at around 300 million and is having troubling finding ways to grow.

But Facebook, which owns Instagram after buying it for $1 billion in 2012, is still far bigger than its photo-sharing sibling. It has about 1.6 billion users, and recently celebrating having 1 billion of them on the site in just one day.

Instagram is now making a major addition to Facebook's revenues, and is expected to generate $1.5 billion in money from ads this year. When Facebook bought the company, the hugely expensive deal was met with skepticism – but it has been able to use Facebook's advertising technology to help boost its revenue and provide extra money to its parent.

More than 80 per cent of people using the app are outside its home of the US. And the users share more than 95 million photos and videos each day, generating over 4.2 billion likes.