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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.

About Application Gateway Calculator

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

Worked example

With the default values below, Application Gateway Calculator returns Capacity Units to Provision of 30. Change any input above and every figure here is recalculated in your browser.

Inputs used

Throughputaccepts 1–1,000,000 Mbps
200 Mbps
New connections per secondaccepts 1–1,000,000 cps
300 cps
Persistent connectionsaccepts 1–100,000,000 connections
6,000 connections
WAF (web application firewall) enabled
Yes
Throughput per capacity unitaccepts 1–1,000 Mbps
10 Mbps

Results

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. 1Values used
  2. 2Application Gateway
  3. 3Capacity Units to Provision= 30
  4. 4Units Implied by Throughput= 20.00
  5. 5Units Implied by New Connections= 6.00
  6. 6Units Implied by Persistent Connections= 2.40
  7. 7Gateway Instances= 3
  8. 8Dimension Setting the Size= Throughput

Assumptions and limits

  • The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

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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