Estimate how much data YouTube delivers every day.

Data delivered by Youtube per day = People watching youtube in one day X Avg number of videos watched X Avg length of video in minutes X Size of a one-minute video X %adjustment for CDNs/Online caching

Assumptions

There are no specific events going on on that day.

People watch an average of 3 videos if they are on Youtube. People watch only one video if it is an embedded Youtube video

Size of a one-minute video is around 20 MB

Assuming 20% of videos are cached by CDNs

Calculations

People watching youtube in one day can be calculated by dividing the demographics into 3 groups

Group	Size (USA)	% watching	# of videos watched per day	# of total videos watched	Notes/Assumptions
Teens	50M	5%	1	2.5M	Teens are mostly watching TikTok etc. and watching youtubes vides as embedded videos
Adults	150M	20%	3	90M	Watching videos on youtube
Senior Citizens	100M	10%	3	30M	This group is mostly watching videos on TV or other channels instead of on Youtube

Data delivered by Youtube per day = (2.5M+90M+30M) * 5 min * 20 MB * 80% (20% delivered by CDNs)

= 9800 Million MB per day ~ 9.8 Million GB of data per day

Edge cases

The number will widely vary according to days and nature of videos. A viral video can increase it and a game day can decrease the number significantly.