Slack Usage Sizing: Estimate How Many People Open It on a Given Day

Estimate the number of people around the world who use Slack on a given day. Walk through your reasoning step by step, state each assumption, and arrive at a point estimate with a sensible range. ```hint Bound the population first Slack is a workplace tool that organizations roll out to their staff. Decide which people could realistically have it at work, how it competes for those seats, and what "daily" means for a tool used mostly on workdays. ``` ### Clarifying Questions - Does "active" mean opening Slack at least once that day, or sending at least one message? - Should the number describe a typical weekday, or an average across all seven days including weekends? - Are free workspaces, guest accounts and community workspaces (open-source projects, hobby groups) included, or only paid business seats? - Is the scope global across desktop, web and mobile, counting each person once even if they belong to several workspaces? ### What a Strong Answer Covers - A clear definition of a daily active user for a workplace tool, including how weekends are treated. - An explicit equation that narrows from a working population to Slack seats to daily users. - Each assumption labeled with a round number and a reason, including Slack's position against chat tools bundled into larger office suites. - Correct arithmetic, a range showing which assumptions matter most, and a sanity check against a public anchor or a second method. ### Follow-up Questions - Which assumption moves your answer the most, and what data would you look for to narrow it? - Re-estimate from the company side: how many organizations use Slack, and how many seats does a typical one have? - How would you expect Slack's ratio of daily to monthly users to compare with that of a consumer messaging app, and why?