Analyzing the 2019 Numbers for Different Office 365 Workloads

Office 365 with Teams

Once More Into the Office 365 Crystal Ball

A year ago, some inspired guesswork allowed me to come up with numbers of active users for the major Office 365 workloads. Time passes on, and the official count for monthly active Office 365 users has reached 200 million, a gain of 45 million over the year. That’s healthy growth for any service.

Microsoft records Office 365 usage as monthly active users. This number is not the total of licenses sold to customers. Instead it reflects those who have licenses who log on and use the service at least once a month (which is not much for anyone using Office 365). A definition of what monthly active users is for an Office 365 workload is:

The maximum daily users performing an intentional action in the last 28-day period across the desktop client, mobile client, and web client.

An intention action is something like uploading a document to a SharePoint Online document library, sharing a document, starting a new conversation in a Teams channel, participating in a video meeting, or sending email. Microsoft records these signals in the Graph and calculates usage after de-duplication based on user identifier (the GUID for an Office 365 user account).

SharePoint Online Gets to 100 Million

Microsoft reports Office 365 numbers roughly every six months. What’s recently changed is that Microsoft has started to disclose some numbers for individual workloads. At the Microsoft Ignite 2019 conference, Jeff Teper said that SharePoint Online has more than 100 million monthly active cloud users.

The interesting question to ask is why the other 100 million Office 365 users don’t use SharePoint Online? Perhaps it’s because a lot of SharePoint activity is still on-premises. After all, in April 2017, Teper claimed that SharePoint had more than 200 million users (both cloud and on-premises); if we assume that the total is larger now, it points to lots of on-premises activity. Which is a good reason for why Microsoft bought in October.

Teams Growing Strongly

Microsoft CVP for Office 365 Jared Spataro said on November 19 that Teams has more than 20 million daily active users, a growth of seven million since July 2019, when Microsoft first claimed to have more users than Slack. A Slack person sought to downplay the Teams number to Paul Thurrott, saying that “you can’t transform a workplace if people aren’t actually using your product.” Well, my experience of using Teams daily is that it is a product that people do use and like using.

The Teams number is for daily active users. The monthly number is higher. For instance, when Microsoft claimed 13 million daily active users in July, they also said that their weekly number was 19 million, or roughly 50% higher. A reasonable guess for the monthly number is north of the 30 million mark. And what’s sure is that with the size of Office 365 and the July 2021 retirement date for Skype for Business Online getting closer, Teams has a lot of room to grow.

Microsoft doesn’t publish a number for Exchange Online. There’s lots of hybrid organizations inside Office 365, but relatively few on-premises mailboxes remain in these organizations. Most mailboxes connected to Office 365 accounts are in Exchange Online, possibly around 180-185 million monthly active mailboxes.


Despite the “Year of Yammer” getting considerable publicity at Microsoft Ignite 2019 and some positive signs that Yammer is embracing the Office 365 ecosystem, I don’t see huge growth for Yammer. Microsoft hopes that a new client and closer connections between Yammer, Teams, and Outlook will make the application a more compelling offering for enterprise tenants. The jury’s out on this and we’ll see how customers respond as the new functionality drops over the course of 2020.


As I noted last year, Microsoft doesn’t give many clues about how Planner is doing. A new effort is spinning up to integrate the task items generated by Planner, To Do, Outlook, and Teams in the Office 365 substrate. Being able to work with the same data through your application of choice makes a heap of sense, but we don’t know how this will affect Planner.

Summarizing the Numbers

Table 1 summarizes my guesswork. I was plain wrong with the SharePoint Online and Teams numbers last year (a possibly I cheerfully accepted at the time), but now that Microsoft has given some data, we can track the numbers better in the future.

Workload (monthly active users) December 2018 (as per previous article) December 2019
Office 365 (overall) 155 million 200 – 205 million
Exchange Online 135-150 million 175 -185 million
SharePoint Online 110 – 130 million 100 – 105 million
Teams 25-30 million 30-35 million
Yammer 5- 8 million 6 – 9 million
Planner 3 million 4 million

Table 1: Inspired Guesswork for the Numbers using the Office 365 Workloads

Aren’t statistics just great fun?