Calculate the overall addressable market for Slack.

This inquiry pertains to the overall market size that Slack could potentially serve, commonly known as the "total addressable market" or TAM. It involves estimating the possible sales for Slack if it were to capture the entirety of its potential market. To effectively respond to this question, it is essential to grasp the product itself, the demographics of prospective users, and in this context, the size and growth of businesses and corporations that may use Slack, including both local and international markets. Fundamentally, Slack functions as a communication platform designed to enhance conversations and promote efficient collaboration within organizations. For this estimation, the primary user base would consist of businesses, encompassing both small and medium enterprises (SMEs) as well as larger corporations, and potentially some educational institutions. To thoroughly address the question, two methodologies could be employed. One approach could be a 'top down' method, utilizing industry reports or other secondary data to estimate the overall market size, subsequently refining this figure based on the segment that Slack might realistically capture. Alternatively, a 'bottom up' approach could be taken, where one estimates the number of potential customers and multiplies this by the expected revenue per customer.

Based on the 'top down' method, recent market research indicates that the worldwide market for collaboration software is projected to reach $13.5 billion by 2023. We can use this figure as a foundation for our estimation. If we assume that Slack can secure 10% of that market, its total addressable market would be around $1.35 billion. Nonetheless, this figure does not include other possible markets, such as the education sector, which could greatly expand the total addressable market.

To begin with a 'bottom up' approach, we should first estimate the number of businesses that employ more than 10 individuals, as we will assume this is the minimum size required for Slack to be beneficial. There are approximately 200 million such businesses globally. If we assume that 5% of them could potentially utilize Slack, that results in around 10 million businesses. Next, if we estimate the average revenue per business at $100 per month (considering Slack's pricing ranges from free to $12.50 per user per month, with an average business size of 20 employees), the total addressable market would amount to $12 billion annually. It is important to note that these estimates are based on several assumptions, and the actual total addressable market is likely to fall somewhere in between these figures.