Explanation
Why the waste happens and who it affects.
Classic profiles that have grown to dozens or hundreds of routing rules, or many custom domains, pay these meters every hour of every month. Standard and Premium do not charge per routing rule or for the first 100 domains, and Microsoft states they have a lower total cost of ownership.
Classic is also a retiring product. Microsoft no longer allows new classic profiles or new domain onboarding, and Front Door (classic) retires on March 31, 2027, so these profiles have to move anyway. Azure Advisor flags classic profiles with a large number of domains or routing rules, recommending migration to Standard or Premium to save costs. Migration is not automatically cheaper for every shape of workload: Microsoft's own examples show request-heavy workloads and estates with many separate profiles can cost more after a one-to-one migration, so the cost has to be modeled first.
Billing model
The pricing dimensions that drive this cost.
Classic and Standard/Premium bill on different dimensions; Microsoft's pricing comparison gives example rates.
- Classic routing rules
- Each rule billed per hour, at a higher rate for the first 5 rules than for additional rules (Microsoft's example rates are 0.03 USD and 0.012 USD per rule per hour)
- Classic domains and inbound data
- Custom domains beyond the first 100 billed monthly per domain, and inbound data transfer billed per GB
- Classic egress
- Edge-to-client data transfer priced across 5 zones at higher unit rates than Standard and Premium
- Standard and Premium
- A monthly base fee per profile plus per-request and per-GB charges, with routing rules and the first 100 custom domains free
How to detect
5 checks to find it in your estate.
- Review the Azure Advisor cost recommendation Consider migrating to Front Door Standard/Premium, raised when a classic profile contains a large number of domains or routing rules
- List Microsoft.Network/frontDoors resources and count routing rules and frontend endpoints per profile; every rule is billed hourly, so profiles with dozens or hundreds of rules carry the largest configuration charge
- From the classic invoice and the Request Count and Billable Response Size metrics, estimate the Standard or Premium cost with the pricing calculator as Microsoft's cost assessment describes, and compare it with the current bill
- Count how many classic profiles exist per application or environment, since migrating each one to its own Standard or Premium profile adds a base fee per profile
- Look for classic resources left behind after a completed migration; Microsoft recommends deleting them and sends an Azure Advisor reminder
How to fix
4 ways to remove the waste.
- Migrate classic profiles to Standard or Premium with Microsoft's zero-downtime migration tool, choosing Standard unless managed WAF rule sets, bot protection or Private Link to origins are needed
- Where many classic profiles exist, consolidate them into a small number of multi-endpoint Standard or Premium profiles instead of migrating one-to-one, to avoid multiplying base fees
- For request-heavy workloads, model the per-request meter before migrating, and remove unnecessary classic profiles such as temporary test environments first
- Delete the classic resource after migration completes, and finish migrations well before the March 31, 2027 retirement, after which classic resources can no longer be managed
Documentation
Vendor references for pricing and configuration.