WhatsApp said 55 billion messages are sent each day on platform, and users also share 4.5 billion photos and one billion videos per day.
"Whether it's sharing personalized photos and videos, connecting through video calling, or keeping friends updated throughout the day with Status, communicating on WhatsApp has never been easier or more personal," WhatsApp said in the blog.
At F8 last April, Facebook CEO Mark Zuckerberg said messages sent on Facebook Messenger and WhatsApp combined totaled 60 billion per day.
Facebook last month said it had reached two billion monthly users, and yesterday noted that as of June it had 1.32 billion daily users.
Asked yesterday by an analyst about WhatsApp's revenue prospects compared to Messenger, Facebook's CFO, David Wehner, said the company isn't sharing detailed engagement figures by messaging platform, but noted differences in usage for each by region.
"WhatsApp has demonstrated significant engagement with crossing a billion daily actives. So I think that indicates the engagement that you have on that platform. There are different geographies where the messaging platforms are stronger," he said.
Zuckerberg said it was "still early on the monetization side" for WhatsApp.
Facebook also reported metrics for Stories for WhatsApp and Instagram, each of which have 250 million daily users. More users of course supports Facebook's ad business, which received $9.16bn in revenues, up 47 percent year-on-year.