Market-sizing exercise: how many people actively use Dropbox in a month

Estimate how many people use Dropbox, the cloud file storage and sharing service, in a typical month. Lay out the structure of your estimate, state each assumption as you make it, and finish with a single number and a sense of how confident you are in it. ```hint Define, then segment Decide exactly what someone must do within a month to count, then split the population by why they would need a cloud file service in the first place. ``` ### Clarifying Questions - Should the estimate cover the whole world, or one country or region? - What counts as using Dropbox in a month: a deliberate action in the app or on the website, or would background file syncing from the desktop app count too? - Are people who use Dropbox through an employer's business or team plan included, or only individual accounts? - Should people who open a shared Dropbox link without signing in be counted as users? ### What a Strong Answer Covers - A precise definition of a monthly user before any arithmetic. - An equation that segments the population, for example by work, study and personal use, instead of one blanket percentage. - Each assumption labeled as an assumption, with round numbers and reasoning about bundled competitors such as Google Drive, OneDrive and iCloud. - Correct arithmetic and a final figure with a plausible range. - A sanity check against an independent anchor. ### Follow-up Questions - Which single assumption moves your answer the most, and how would you get a better number for it? - How would the model change if you were asked for daily rather than monthly users? - Rerun the estimate for one country only. Which inputs change and which stay the same?