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Application Gateway Calculator

Size a cloud application gateway in capacity units from throughput, new connections and persistent connections, with a WAF uplift.

Inputs

Mbps
cps
connections
Mbps

Capacity Units to Provision

30

Units Implied by Throughput

20.00

Units Implied by New Connections

6.00

Units Implied by Persistent Connections

2.40

Gateway Instances

3

Dimension Setting the Size

Throughput

Step by step

  1. Values used

    Throughput = 200 Mbps; New connections per second = 300 cps; Persistent connections = 6,000 connections; WAF (web application firewall) enabled = Yes; Throughput per capacity unit = 10 Mbps

  2. Application Gateway

    capacity units = max(throughput ÷ per-unit throughput, new connections ÷ 50, persistent connections ÷ 2500), multiplied by 1.5 when a WAF is enabled.

  3. Capacity Units to Provision

    = 30

  4. Units Implied by Throughput

    = 20.00

  5. Units Implied by New Connections

    = 6.00

  6. Units Implied by Persistent Connections

    = 2.40

  7. Gateway Instances

    = 3

  8. Dimension Setting the Size

    = Throughput

How it works

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.

Formula

Application Gateway

capacity units = max(throughput ÷ per-unit throughput, new connections ÷ 50, persistent connections ÷ 2500), multiplied by 1.5 when a WAF is enabled.

50
New connections per second one capacity unit sustains
2500
Persistent connections one capacity unit holds

Frequently Asked Questions

How is Application Gateway calculated?

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.

Why does Application Gateway matter?

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.

What values do I need to enter?

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.

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