Cost an App Service plan from its instance rate, autoscale range and average load, with reserved-instance discounts.
An App Service plan bills every running instance by the hour regardless of how many apps are deployed into it, so the cost driver is the instance count that autoscale settles at rather than the number of web apps. Deployment slots run on the same plan instances, which is why a staging slot is free in cost but not in capacity. Plans are routinely left at a fixed high instance count 'for safety', and the gap between the average and the pinned-maximum figure here is the money that autoscaling would return; reserved instances on Premium v3 add another 35–55% but lock the tier for the term, so confirm current rates in the Azure pricing calculator.
Azure App Service Cost
average instances = min + (max − min) × average load; monthly = average instances × instance rate × commitment factor × 730 + IP-based TLS bindings.
average instances = min + (max − min) × average load; monthly = average instances × instance rate × commitment factor × 730 + IP-based TLS bindings. An App Service plan bills every running instance by the hour regardless of how many apps are deployed into it, so the cost driver is the instance count that autoscale settles at rather than the number of web apps. Deployment slots run on the same plan instances, which is why a staging slot is free in cost but not in capacity.
Plans are routinely left at a fixed high instance count 'for safety', and the gap between the average and the pinned-maximum figure here is the money that autoscaling would return; reserved instances on Premium v3 add another 35–55% but lock the tier for the term, so confirm current rates in the Azure pricing calculator.
This calculator takes 8 inputs: Instance rate, Minimum instances, Maximum instances, Average position in the autoscale range, Billed hours per month, Commitment term, IP-based TLS bindings, Price per IP-based TLS binding. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.