Cloud Egress and Networking Costs: The Complete Guide

What Is Data Egress?

Data egress refers to data leaving a cloud provider's network. Cloud providers charge for outbound data transfer because it consumes their internet bandwidth capacity. Inbound data transfer (data entering the cloud from the internet) is always free on all major providers.

Egress charges apply in three primary scenarios: data transferred from cloud instances to the public internet (the most expensive), data transferred between cloud regions operated by the same provider, and data transferred between availability zones within the same region (cheapest inter-cloud transfer). Understanding which category your traffic falls into is essential for accurate cost modeling.

Egress Pricing Tables (2026)

Approximate US/EU region pricing. Egress from Asia-Pacific, Middle East, and South America is typically 15–40% higher.

Inter-Region Data Transfer

Data transferred between cloud regions operated by the same provider is billed at inter-region transfer rates, which are lower than internet egress but not free. AWS charges $0.02/GB for US inter-region transfers and up to $0.08/GB for transfers involving Asia-Pacific or South America. Azure and GCP have similar pricing structures.

For disaster recovery architectures with continuous cross-region database replication, inter-region transfer costs can become significant. A database replicating 1TB of changes per day across regions would generate approximately $20–80/day ($600–2,400/month) in inter-region transfer fees alone.

Inter-AZ Data Transfer

All three providers charge $0.01/GB in each direction for data transferred between availability zones within the same region. This is the lowest tier of egress pricing but can accumulate rapidly for distributed architectures that constantly communicate between AZs.

A 3-tier application with web, application, and database tiers spread across 3 AZs for redundancy, generating 10TB of inter-tier traffic per day, would produce approximately $3,000/month in inter-AZ transfer fees. Architects should consider whether the latency and data locality benefits of cross-AZ replication justify the ongoing transfer cost.

NAT Gateway: The Hidden Cost

AWS NAT Gateway is frequently cited as one of the most unexpected cost drivers. NAT Gateway pricing has two components: an hourly charge ($0.045/hr = $32.40/month per gateway) plus a data processing charge ($0.045/GB) on all traffic that flows through it.

For applications in private subnets that access AWS services (S3, DynamoDB, ECR, SQS), replacing NAT Gateway with VPC Endpoints eliminates the per-GB processing fee and is typically much cheaper. A workload downloading 10TB/month from S3 via NAT Gateway pays $450/month in processing fees. The same traffic through a Gateway VPC Endpoint for S3 is free.

CDN Optimization for Egress Reduction

Content Delivery Networks cache content at geographically distributed edge locations, reducing both latency for end users and egress charges from the origin servers. CDN pricing ($0.006–0.012/GB) is significantly lower than direct origin egress pricing ($0.085–0.09/GB for the first 10TB).

For a website serving 100TB/month of static content (images, video, downloads) without CDN: approximately $8,500/month in egress. With CDN achieving 70% cache hit rate: 30TB of origin egress ($2,550) + 100TB of CDN delivery ($1,200) = $3,750/month — a 56% reduction.

Strategies to Reduce Egress Costs

• Enable CDN for all public-facing assets. Even a 50% cache hit rate halves your origin egress bill for static content.
• Use VPC Endpoints for AWS service communication. S3, DynamoDB, ECR, and most other AWS services support endpoints that bypass NAT Gateway.
• Compress API responses. Enable gzip/Brotli compression on web servers and APIs. Text-based responses typically compress 60–80%, directly reducing bytes transferred.
• Optimize image and video delivery. WebP images are 25–35% smaller than JPEG. H.265 video is 40–50% smaller than H.264 at equivalent quality. Serving compressed formats reduces CDN and egress volumes proportionally.
• Evaluate AWS CloudFront vs third-party CDN. CloudFront Origin Shield adds an additional caching layer that can dramatically reduce origin requests for high-traffic content. Third-party CDNs like Cloudflare often have competitive or cheaper pricing for high-volume deployments.