Azure firewall and networking cost optimization is mostly about three things: choosing the right tier for the traffic you actually have, stopping data from leaving when it does not need to, and deleting the gateways and IPs that bill around the clock for nothing. Networking rarely tops the bill, but it is one of the most over-provisioned categories because it gets architected once and then never revisited.
This article is part of our Azure cluster. Start with the complete guide to Azure cost optimization, the pillar this piece links up to, for how networking fits the wider estate. Trimming network cost is the Cut step of our See, Cut, Lock, Run method applied to the connectivity layer.
Pick the right Azure Firewall SKU
Azure Firewall is billed on a deployment charge plus data processed, and the SKU you choose sets the floor. The Standard SKU covers most filtering needs. The Premium SKU adds capabilities such as TLS inspection and intrusion detection at a higher rate, and many teams deploy it for features they do not use. The Basic SKU targets small environments with lower throughput at a lower price. The first move is matching the SKU to the security requirement that is genuinely in force, not the most capable tier by default.
Consolidation is the second move. Running a separate firewall in every spoke is expensive; a hub-and-spoke topology with a central firewall and Azure Firewall Manager policies often serves the same security posture for far less. Each redundant firewall instance carries its own deployment charge whether or not it processes meaningful traffic.
Two meters drive most networking surprise: data processed by the firewall and gateways, and outbound data transfer leaving Azure. Both scale with traffic and both are easy to ignore until the bill jumps. Attribute them by resource and tag before you try to cut them, because you cannot reduce traffic you have not located.
Control bandwidth and egress
Outbound data transfer is charged when data leaves an Azure region or the Azure network, and it is the networking cost that scales worst as you grow. The levers are architectural: keep chatty services in the same region and availability zone where possible, cache and compress data served to the internet, use private connectivity for cross-service traffic, and place a CDN in front of high-volume static content so requests are served from the edge rather than repeatedly leaving the origin. The cross-cloud mechanics of why leaving costs so much are covered in Azure bandwidth and egress pricing.
Networking cost climbing without a clear owner?
Our Azure cost audit maps every gateway, firewall, and egress meter to a resource and a team, then models the consolidation and routing moves available. On the performance model, you pay only from realized savings. No savings, no fee.
Book an Azure cost audit →NAT Gateway, private endpoints, and gateways
NAT Gateway provides reliable outbound connectivity and is billed on an hourly resource charge plus data processed. It is usually the right choice over older outbound patterns, but it should be sized and shared at the subnet level it actually serves, not spun up per workload. Private endpoints each carry an hourly charge and a data-processing charge; they are valuable for security, but unused or duplicated private endpoints are pure waste, and they accumulate as projects come and go. VPN and ExpressRoute gateways bill continuously by gateway SKU, so an over-specified gateway for a low-bandwidth link is a recurring overpay.
Delete the orphans
Networking is where orphaned resources hide best. Unassociated public IP addresses now bill on the Standard SKU whether or not they are attached. Idle load balancers, empty NAT Gateways, gateways for decommissioned connections, and private endpoints pointing at deleted services all keep charging. These are the same low-risk wins covered in how to find idle and orphaned Azure resources, and networking should be a first stop on that hunt.
| Resource | How it bills | Main lever |
|---|---|---|
| Azure Firewall | Deployment + data processed | Right SKU, central hub firewall |
| Egress / bandwidth | Per GB leaving region or Azure | Co-locate, cache, CDN, compress |
| NAT Gateway | Hourly + data processed | Share at subnet, right size |
| Private endpoints | Hourly + data processed | Remove unused and duplicates |
| Public IPs / gateways | Hourly per resource | Delete orphans |
SKU names and billing dimensions above reflect Azure networking as of May 2026. Verify current Firewall SKUs, public IP charges, and gateway pricing in Azure documentation before changing production networking, as these meters change.
The Azure Cost Optimization Field Guide includes the networking teardown checklist and the egress reduction patterns we apply on engagements. It is the downloadable companion to this article.
The short version
Match the Firewall SKU to the security you actually use and consolidate to a central hub firewall, attribute and reduce egress and data-processing meters, size NAT Gateway and gateways to real traffic, remove unused private endpoints, and delete orphaned public IPs and idle gateways. To work the whole estate methodically, follow how to run an Azure cost optimization assessment. When you want it executed across every subscription, that is exactly what our Azure cost optimization service delivers.