Cloud data transfer costs represent 10-18% of total cloud spending and are among the most overlooked yet impactful drivers of cloud bills. Ingress (data moving into cloud infrastructure) is typically free across all major providers, while egress (data leaving cloud infrastructure) incurs charges that vary significantly by destination, volume, and provider. Understanding the nuanced pricing models—from inter-AZ charges (0.01/GB) to internet egress fees (0.09-$0.12/GB) to cross-region transfers—is essential for cost-effective cloud architecture. The key insight: architectural decisions made early determine whether data transfer becomes a minor line item or a budget-crushing 15% tax on every workload.
What This Cheat Sheet Covers
This topic spans 15 focused tables and 124 indexed concepts. Below is a complete table-by-table outline of this topic, spanning foundational concepts through advanced details.
Table 1: Ingress vs Egress Fundamentals
| Concept | Example | Description |
|---|---|---|
Upload 10 TB to S3: $0 | • Data flowing into cloud infrastructure • universally free across AWS, Azure, GCP, and all major providers—no charges for uploads, writes, or inbound transfers. | |
Download 10 TB from S3: $900 | • Data flowing out of cloud infrastructure to the internet, other regions, or external destinations • charged at 0.08-0.12/GB after free tier. | |
EC2 → public internet: $0.09/GB | • Data transferred from cloud to the public internet • most expensive egress category • first 100 GB/month free on AWS, Azure, GCP. | |
Same-region S3 → EC2: Free | Data transfer within the same region between AWS services (e.g., S3 to Lambda) is typically free if using private IPs or gateway endpoints. |