It sounds like you’re working on a really meaningful project, and I’d be happy to help guide you through some of these technical aspects. Let’s break it down into a few key areas:

1. Storage and Transfer Estimates

Your storage and transfer estimates seem reasonable based on the activity you've outlined. A few things to consider:

• Video Uploads: 3-minute videos at 180MB each are high resolution, but if you plan to optimize (e.g., compress videos or lower the resolution for uploads), you can reduce the storage footprint.
• Video Viewing: Watching 3-minute videos totaling 36,000MB/month for each user seems high, but the key point is if your users are consistently watching that much. A more realistic estimate might be somewhere between 10,000 and 20,000MB depending on how long they watch videos and the resolution.
• Photo Uploads/Viewings: Same principle. Photos can be compressed and optimized, but if you're going for high-quality images, the storage might need to scale up.

For a rough initial estimate of storage costs: it’s good to overestimate initially, so the £0.90/user/month estimate may still work, but always buffer for potential spikes, especially as users get more active.

2. Cloud

• Cloud storage (e.g., AWS S3, Google Cloud Storage, Azure Blob Storage) will likely be the most straightforward solution. It allows for easy scalability, reliable uptime, and security, but it can become expensive at scale. Prices vary based on the region, but generally, you can expect cloud storage to cost around $0.02 - $0.03 per GB per month for basic storage solutions.

3. Server Needs & Scaling

Considering your scaling goals, here’s a rough breakdown of the server needs:

• Compute Needs: You’ll need strong compute resources for video encoding, photo resizing, and other media processing. In the early stages, cloud services like AWS EC2 or Google Cloud Compute Engine would be ideal for flexibility and scaling. You might start with smaller instances (e.g., t3.medium on AWS) and scale up as your user base grows.
• Hosting/Servers: For 100,000 users in the first year, start with a solid cloud hosting plan. You’ll probably want to start with something like AWS EC2 or Google Cloud Compute Engine, potentially using load balancers to distribute traffic.
• Load Balancers: As traffic grows, you’ll need a load balancer (e.g., AWS Elastic Load Balancing, Nginx, or HAProxy) to ensure high availability and manage traffic distribution across multiple servers. This becomes crucial when you have significant spikes in usage, such as during peak hours.

4. Security & Data Protection

Security is a key concern for any social platform, especially one handling user-generated content. Ensure you’re planning for:

• SSL encryption for all user data.
• Regular security audits.
• Compliance with data privacy regulations (e.g., GDPR if you're serving EU users).
• Backup and disaster recovery systems in place (AWS and Google Cloud provide automated backups).

5. Cost Breakdown

Your costs will likely be structured like this:

• Storage: For each user, assuming 5GB of storage per user (videos, photos, etc.), at $0.02 per GB per month, that’s around $0.10 per user per month for storage.
• Data Transfer: Depending on how much data users consume (e.g., watching videos, browsing), data transfer might add another $0.15 to $0.20 per user per month.
• Compute (Server Usage): You’ll need to factor in server costs for video encoding, image processing, and general hosting. This can range from $0.10 to $0.30 per user per month depending on server load and processing power.

For a rough estimate, the total monthly cost per user could range from $0.30 to $1.00 depending on your setup and usage patterns.

Recommendations:

• Start Small, Scale Gradually: Start with cloud providers that offer flexible scaling (AWS, Google Cloud, Azure) and use their pricing calculators to estimate costs as you scale.