How would you estimate the space required for Google Photos?
If you are PM for google photos, Please provide estimate in terabytes, how much space would you allocate when launching this product? Consider for designing for the world.
Google- Anushka Garg
Clarification:
Before I dive into solutions, let me ask a few questions to make sure I understand the scope correctly.
- Google Photos is a service where smartphone users can choose from either the free service and the premium service. For free service, user can
- Have unlimited storage to upload all their photos at standard quality.
- Have about 5GB for uploading videos.
- Access their photos from the cloud.
- Access value adding features such as auto generated album, picture editing etc.
- It’s available to both IOS and Android.
- Is this understanding correct? [Yes]
- Can I focus on the free service users, as they are the majority of user base. [Sure]
- Is this forecast for 6 months, 1-yr or 3-yrs? [3-yrs]
- For Space, can I just focus on the total size of all the pictures and ignore the added space requirement due to redundancy? [Sure]
- How is Google Photos launched to users?
- Is it available to all the Android versions after launched [Yes]
- Will it be preloaded in new Android phones which are launched after Google Photos? [Yes, it will be preloaded in Android phones with new OS releases]
- How frequently are Android OS versions released? [about once a year]
- For IOS users they always have to download the app? [Yes]
- Is this estimate for the world wide service? [Yes]
Approach
I will approach this question by estimating the # of users in 3-yrs, multiply by avg account age by the end of 3-yrs and multiply by the avg volume of photo upload per user per year.
Users
To estimate the number of Google Photos users in 3-years, I will estimate the # of Android and IOS phones in 3-years, then make some assumptions of the market share of Google Photos in Android and iOS respectively.
- Smartphone user in 3-years
- World population: 7 Bn
- NA+JP+EU: 1Bn
- China: 1.5Bn (No google services, exclude from calculation)
- Rest of the world: 4.5Bn
- Assuming Smartphone penetration in NA+JP+EU is 90%, RoW: 50%, this gives a total of (0.9+2.25)=~3bn
- Assuming Android Phone share of the global smartphone market is 80%, this gives 2.4 bn Android devices and 0.6bn IOS devices.
- World population: 7 Bn
- Assuming user switch their phone every 3-yrs globally, so in 3-years all active android devices are already preloaded with Google Photos
- Assuming Google Photos market penetration in 3-years:
- Android Devices: 40% (Higher due to preloading) -> 0.96bn
- IOS Device: 10%: -> 0.06bn
- Total: ~1bn active users
Average Account Age
- Assuming a steeper user growth curve in the first 1-yr following launch, so the average account age in 3-yrs is likely about 2 years.
Volume of Photo Uploaded per user per year
- Dividing Google Photo users by usage:
- Power Users: 10% (10 photos per day)
- Active Users: 30% (3 photos per day)
- Typical Users: 50% (1 photos per day)
- Tail Users: 10% (0.3 photos per day)
- So the # of photos uploaded per user per year is about (10%*10+30%*3+50%*1+10%*0.3)*365=(1+0.9+0.5+0.03)*365=~900
- Standard quality picture is about 2.5MB per pic.
- Total volume of pictures uploaded per user per year is 900*2.5MB=2.25TB
Conclusion:
The space required for Google Photos 3-years post launch is about 2.25TB*2*1bn=4.5bn TB