Senior Vice President, Engineering for Google Vic Gundotra has revealed in a blog post that Google+ now has more than 400 million registered users.

Around a quarter of these are active users who use the service on a monthly basis.

100 million active users is a pretty impressive achievement for this product which was launched just last year.

Vic said:

This week we also hit an important milestone-over 400,000,000 people have upgraded to Google+. It was only a year ago that we opened public sign-up, and we couldn’t have imagined that so many people would join in just 12 months. While Google+ is all about creating a better experience across Google, it’s also a destination. And here too, I’m happy to report that we have just crossed 100,000,000 monthly active users on Google+ (plus.google.com and mobile app).