Network Egress Costs in Azure Explained

Egress Cost Categories

Azure data transfer costs depend on the source and destination:

Real-World Egress Cost Examples

Scenario 1: SaaS application serving global users

A web application hosted in East US serving 50 TB of data per month to end users worldwide:

• First 100 GB: free
• Remaining 50,000 GB at blended rate (~$0.082/GB): approximately $4,100/month

This is a substantial bill item. Introducing a CDN can shift much of this traffic to CDN edge nodes at lower effective rates and with better user latency.

Scenario 2: Multi-region active-active database

A service replicating 1 TB of database changes per month from East US to West Europe:

• 1,024 GB × $0.07/GB (cross-continental): approximately $72/month

Modest at 1 TB but scales linearly. At 10 TB of replication traffic, cross-continental egress reaches $720/month.

Scenario 3: Microservices across peered VNets

An architecture where services in VNet A call services in VNet B (same region, peered):

• VNet peering egress: $0.01/GB in each direction
• 100 GB of inter-service traffic: $1/month
• 10 TB of inter-service traffic: $100/month

For high-bandwidth microservices architectures, consider whether services should be in the same VNet rather than peered VNets to eliminate this charge.

Reducing Internet Egress Costs

Azure CDN and Front Door

Azure CDN caches static and semi-static content at edge locations close to users. Cached responses served from edge nodes do not generate origin egress charges. Azure Front Door adds dynamic acceleration, request routing, and WAF capabilities on top of CDN features.

CDN egress pricing varies by Azure CDN product and geographic zone but is often lower than direct Azure egress for high-volume traffic. More importantly, caching dramatically reduces the volume of data served from origin servers.

# Create an Azure CDN profile and endpoint
az cdn profile create \
  --resource-group my-rg \
  --name my-cdn-profile \
  --sku Standard_Microsoft

az cdn endpoint create \
  --resource-group my-rg \
  --profile-name my-cdn-profile \
  --name my-cdn-endpoint \
  --origin my-storage.blob.core.windows.net \
  --origin-host-header my-storage.blob.core.windows.net \
  --query-string-caching-behavior IgnoreQueryString

Compress responses

Enabling compression at the application or CDN layer reduces the bytes transferred for text-based content (HTML, CSS, JSON, XML) by 60–80%. This directly reduces egress charges proportionally.

Region selection

Hosting resources in the same region as your users eliminates or reduces inter-region transfer costs and reduces latency simultaneously. If your users are primarily in Europe, deploying in West Europe rather than East US saves inter-region transfer charges for data that would otherwise flow across the Atlantic.

ExpressRoute and Data Transfer

Azure ExpressRoute provides a dedicated private connection between your on-premises network and Azure. ExpressRoute affects egress pricing in a specific way:

• Metered ExpressRoute: outbound data from Azure to on-premises costs $0.025/GB (cheaper than internet egress at $0.087/GB). Inbound is free.
• Unlimited ExpressRoute: a flat monthly fee covers all data transfer regardless of volume. This becomes economical when monthly transfer volume exceeds approximately 15–20 TB outbound.

For organisations regularly transferring large datasets between Azure and on-premises — for example, backup or analytics workloads — the Unlimited ExpressRoute option can save significantly compared to Metered plans at high volumes.

Architecture Choices That Affect Egress

Some common architectural patterns generate significant egress that can be redesigned to reduce costs:

Chatty cross-region microservices

Services deployed across multiple regions that frequently call each other incur cross-region peering charges on every call. Solutions: deploy dependent services in the same region; use message queues (Service Bus, Event Grid) to decouple services and batch messages; review whether cross-region service calls are necessary.

Application servers querying remote databases

Application servers in Region A querying databases in Region B generate cross-region transfer charges on every query response. Move the database to the same region as the application, or use read replicas in the application’s region for read-heavy workloads.

Log and telemetry centralisation

Sending logs and metrics from multiple regions to a central Log Analytics workspace in one region generates inter-region transfer charges. Options: use regional Log Analytics workspaces and cross-workspace queries; reduce logging verbosity; use sampling for high-volume telemetry.

Monitoring Egress Costs

# Query bandwidth costs in Cost Analysis (group by meter subcategory)
az costmanagement query \
  --type Usage \
  --scope "/subscriptions/$(az account show --query id -o tsv)" \
  --timeframe MonthToDate \
  --dataset-granularity None \
  --dataset-aggregation "{\"totalCost\":{\"name\":\"Cost\",\"function\":\"Sum\"}}" \
  --dataset-grouping "[{\"name\":\"MeterSubCategory\",\"type\":\"Dimension\"},{\"name\":\"ServiceName\",\"type\":\"Dimension\"}]" \
  --dataset-filter "{\"dimensions\":{\"name\":\"ServiceName\",\"operator\":\"In\",\"values\":[\"Bandwidth\"]}}" \
  --query "properties.rows | sort_by(@, &[0]) | reverse(@)" \
  --output table