Size a cloud application gateway in capacity units from throughput, new connections and persistent connections, with a WAF uplift.
A cloud gateway bills a single capacity unit that bundles throughput, connection-establishment rate and connection-holding capacity. You are charged for whichever dimension is highest, and rule inspection in a WAF adds roughly half again to the compute cost. Autoscaling a gateway on throughput alone leaves you short whenever the workload is many small short-lived requests, because the new-connection dimension saturates long before the megabits do.
Application Gateway
capacity units = max(throughput ÷ per-unit throughput, new connections ÷ 50, persistent connections ÷ 2500), multiplied by 1.5 when a WAF is enabled.
capacity units = max(throughput ÷ per-unit throughput, new connections ÷ 50, persistent connections ÷ 2500), multiplied by 1.5 when a WAF is enabled. A cloud gateway bills a single capacity unit that bundles throughput, connection-establishment rate and connection-holding capacity. You are charged for whichever dimension is highest, and rule inspection in a WAF adds roughly half again to the compute cost.
Autoscaling a gateway on throughput alone leaves you short whenever the workload is many small short-lived requests, because the new-connection dimension saturates long before the megabits do.
This calculator takes 5 inputs: Throughput, New connections per second, Persistent connections, WAF (web application firewall) enabled, Throughput per capacity unit. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.