Storage, requests and egress cost for cloud object storage.
The classic cloud-bill shock is egress, not storage. If you serve lots of downloads, put a CDN in front or pick a provider with free/low egress. For API-side costs see the cloud & dev APIs.
Free object storage cost calculator — stored GB, requests and egress to your monthly S3-style storage bill.
Three parts: storage per GB-month, request fees, and egress (data transfer out) per GB. Storage is cheap; egress is usually the biggest and most surprising line.
Cloud providers price storage low to attract data, then charge heavily to move it out. High-traffic downloads or video can make egress dwarf storage cost — a CDN or an egress-friendly provider mitigates it.