Estimate the total number of videos on YouTube.

​​​​​​IMO this is the type of structure you need to answer a Google estimation interview question like this.

1. CLARIFY:
   1. Should we be focused on US uploaded videos or global videos? You choose.
   2. Are we thinking about individually upload videos only or should we include movies and shows you can rent? You choose. (I will exclude movies / TV shows.)
   3. Do we need to restrict content by any means - ex. some videos only have music without any graphic content? You choose. (Assume no.)
   4. Is it OK to exclude Youtube TV and Youtube Music? Yes. 
   5. Is this equation for uploads within the year or uploads for the entire life of Youtube? You choose. 
2. BACKGROUND: Youtube is a video platform that is owned by Google. It was bought by Google and now is a Google subsidiary. It allows users to browse content, upload videos, purchase movies and shows and do live streams. It was founded in 2005.
3. EQUATION: Total Videos = # of videos by individuals + # of videos by professional businesses (I am excluding movies / TV shows for rent.)
4. BREAKDOWN UNKNOWN: 
   1. # of videos by Individuals: 
      1. # of Individual Youtube Users: (Both from a viewer and uploader perspective.)
         1. Youtube operates in over 90 countries. It is blocked in others - the biggest being China. 
         2. World Population: 7.8B
         3. Population - Non Youtube Countries: 
            1. China is the biggest population without Youtube (1.4B population).
               1. 7.8B - 1.4B = 6.4B
            2. ~100 countries out of 195 countries in world do NOT have Youtube. Let's assume these countries without Youtube are smaller, so they represent ~40% of remaining world population.
               1. 6.4B * .6 = 3.8B
         4. Population with Internet:
            1. 60% of the world has internet. (Let's assume this percentage remains the same though we have removed ~ 100 countries). 
            2. 3.8B * .6 = 2.3B
         5. Youtube Availability in Internet Regions: 
            1. Assume 90% of population has Youtube if there is Internet. 
            2. 2.3B * .9 = 2B
         6. # of Individual Users: Let's assume 1 account / user.
            1. Average Age of Population: 0-80
            2. People who could use  Youtube: 
               1. 10-80 years old (i.e. 7/8 of population)
               2. .875 * 2B = 1.75B
            3. People who use Youtube: (I.e. non-businesses) 
               1. Assume 75% of eligible age population uses Youtube. Younger segments are much more likely to use Youtube than older segments - guess 90% v. 60%, so we can split the difference. 
               2. 1.75B * .75 = ~1.2B
      2. # of Videos / Individual User: 
         1. Individual User Types: Let's split the individual uesr group into 3 groups. Note - we're assuming individuals have 1 account.

         2. User Type	% of Population	# of People	# of Video Uploads / Week	# of videos / year for each individual	Total videos / Year
            Viewer Only	60%	1.2B * .6 = .72B	0 / week	0	0
            Moderate	20%	1.2* .2 = .24B	1 / every 2 weeks	2 * 26 weeks = 52 videos	.24B * 52 videos = 12.5B
            Influencer	20%	1.2* .2 = .24B	2 / week	2 * 52 weeks = 104 videos / year	.24B * 52 videos = 12.5B

         3. Total Videos by Individuals: 12.5B + 12.5B = 25B

   2. # of videos by businesses:
      1. Types of Businesses: Let's break down the size of businesses by averge number of employees. Majority of businesses in the US are small. Let's assume that rough percentage for the rest of the world. 

         1. Size of Business	% of Employees	Percent of Population	# of People in Population of Youtube Countries	# of Businesses
            Small	10	60%	.6 * 2B = 1.2B	1.2B / 10 = 120M
            Medium	50	20%	.2 * 2B = 400M	400M / 50 = 8M
            Large	100	10%	.1 * 2B = 200M	200M / 100 = 2M
            Extra Large	10,000	10%	.1 * 2B = 200M	200M / 10,000 = 20K

         2. Number of Businesses: 120M + 8M + 2M + 20K = ~130M
      2. Youtube Business Accounts: 
         1. Let's assume that if a country has Youtube, there's a 70% chance the business will be on Youtube. 
         2. 130M * .7 = 91M business Youtube accounts

         3. Size of Business	# of Businesses	# of Businesses on Youtube
            Small	1.2B / 10 = 120M	120M * .7 = 84M
            Medium	400M / 50 = 8M	8M * .7 = 5.6M
            Large	200M / 100 = 2M	2M * .7 = 1.4M
            Extra Large	200M / 10,000 = 20K	20K * .7 = 14K

      3. Youtube Business Account Videos: Let's assume similar to individual consumers that the size of the business correlates to posting history. 
         1.  

            Size of Business	# of Videos / Week	Videos / Year	Total Videos / Year
            Small	1 video / month	1 video per month * 12 months = 12 videos	84M * 12 videos = 1B
            Medium	1 video / month	1 video per month * 12 months = 12 videos	5.6M * 12 videos = 67.2M
            Large	1 video / every 2 weeks	1 video * 26 weeks = 26 videos	1.4M * 26 videos = 36.4M
            Extra Large	1 video / week	1 video * 52 weeks = 52 videos	14K * 52 videos = 728K

         2. Total Youtube Business Videos: 1B + 67.2M + 36.4M + 728K = 1.1B videos
   3. Total Videos / Year: 25B videos by individuals / year + 1.1B videos by businesses / year = 26.1B videos by per 
   4. Total Videos on Youtube: 
      1. Youtube was created in 2005 - approximately 15 years ago (give or take a few months). 
      2. Let's assume that the video posted each year grows by ~ 10% as video posting grows in popularity since 2015, but the platform grew at tiered rates every few years. 
      3. Given that 2021 has just started, let's assume that the total we found applies to 2020. We're assuming a full year in 2005. 

      4. Year	# of Videos
         2020	26.1B
         2019	26.1B / 1.1 = 23.7B
         2018	23.7B / 1.1 = 21.6B
         2017	21.6B / 1.2 = 18B
         2016	18B / 1.2 = 15B
         2015	15B / 1.2 = 12.5B
         2014	12.5B / 1.2 = 10.4B
         2013	10.4B / 1.4 = 7.4B
         2012	7.4B  / 1.4 = 5.3B
         2011	5.3B / 1.4 = 3.8B
         2010	3.8B / 1.4 = 2.7B
         2009	2.7B / 2 = 1.4B
         2008	1.4B / 2 = .7B
         2007	1.1B / 2 = .3B
         2006	.7B / 2.5 = 280M
         2005	.1B / 2.5 = 40M
         Total	149B Youtube videos.

5. CHECK:
   1. The number of videos on Youtube in the early years seems too high.
   2. The total videos in 2005 - 2010 = 5.4. Let's cut that in half (2.7B) given ramp up / popularity in social media is relatively recent within the last decade.
   3. 149B - 2.7B = 146.3B total videos on Youtube.

I took a bottom up approach starting from No/ of Internet users in the world (3.5 billion)

We can assume that Youtube Penetration is 90% of internet-using population (3.2b)

In the Youtube Penetration there are majorly 2 classes - Creators(5%) and Viewers (95%)

Since we are focused on Creators, lets explore this category further.

Of the Creators we have 3 categories

1. Professionals (10%) - Who upload an average of 1 video per week (4 per month)

2. Hobbyists (40%) - Who upload an average of 1 video per month

3.  Indvidual Accounts (50%)- Who upload an average of 1 video per year (1/12 per month

5% of creators give us 160m people

Videos by Professionals/ month - 160m*(0.10)*(4) = 64m

Videos by Hobbysit/ month - 160m*(0.40)*(1) = 64m

Videos by Individuals/month - 160m*(0.50)*(1/12) = 7m

 

Total videeos = 64+64+7 = 135m

Calculated this and it checks out with the sanity checks! Please let me know, if there's any improvement that can be done in this approach.

1. Clarifying - Are all videos included? Or only videos above a certain threshold of duration, visibility setting? Assuming all videos and no filters. Also, does it include videos in last 30 days or since the inception of YT? Assuming last 30 days. If the question was for since inception, I would project backwards and assume a growth % because of network effects. Finally, I'm assuming we're only calculating uploaded videos not live ones (may be they should be. So I would include them if the interviewer asks for them.
2. Videos on YT = Videos from amateurs (Tom, Dick and Harry) + Videos from professional YouTubers (individuals) + Videos from professional (Media houses/businesses)
3. Videos from amateurs = Videos that people upload on important ocassions (like wedding, birthday) + Videos that people upload and keep as private on YouTube = (Families who celebrate on an important ocassions per year X % likelihood that these famlies use YT X % likelihood that they use YT to share videos)/12 + (Individuals who upload videos for personal moments that they don't want to share per month X No. of videos per individual doing such an activity)/12
4. Videos from professional YouTubers (individuals) = Videos uploaded on a weekly basis (because frequence of upload is critical to their success, I'm assuming they do this) X No. of Weeks in a month X Number of YT Content Creators X % of Content Creators who are individuals
5. Videos from professionals (Media houses/businesses) = Videos uploaded on a daily basis (because they are businesses I'm assuming that they upload daily because they have the ability to) X No. of days in a month X Number of YT Content Creators X % of Content Creators who are professional media houses
6. Sanity Check = 500 hours of videos get uploaded every 1 min. So assuming that each video is 10 mins (given that most videos on YT are entertainment and people's attention span doesn't last more than 10 mins for entertainment videos). So that means 3000 videos per min. So the final answer should be in orders of magnitude closeness to 3000 X 60 X 24 X 30 = 130 Million per month.

 

It'll be great to get feedback on this.