What are Azure App Service plans?

An Azure App Service plan defines a set of compute resources for a web app to run. An app service always runs in an App Service plan. Azure Functions also has the option of running in an App Service plan.

When you create an App Service plan in a certain region (for example, West Europe), a set of compute resources is created for that plan in that region. Whatever apps you put into the App Service plan run on those compute resources, as defined in the plan.

Each App Service plan defines:

• Operating system (Windows, Linux)
• Region (West US, East US, and so on)
• Number of virtual machine (VM) instances
• Size of VM instances (small, medium, large)
• Pricing tier (Free, Shared, Basic, Standard, Premium, PremiumV2, PremiumV3, IsolatedV2)

Pricing tiers

The pricing tier of an App Service plan determines what App Service features you get and how much you pay for the plan. The pricing tiers available to your App Service plan depend on the operating system that you select at creation time. These are the categories of pricing tiers:

Each tier also provides a specific subset of App Service features. These features include custom domains and TLS/SSL certificates, autoscaling, deployment slots, backups, Azure Traffic Manager integration, and more. The higher the tier, the more features that are available. To find out which features are supported in each pricing tier, see the App Service plan details.

You can find more comparisons of plans in App Service limits.

PremiumV3 pricing tier

The PremiumV3 pricing tier guarantees machines with faster processors (minimum 195 ACU per virtual CPU), SSD storage, memory-optimized options, and quadruple memory-to-core ratio compared to the Standard tier.

PremiumV3 also supports higher scale via increased instance count, while still providing all the advanced capabilities in the Standard tier. PremiumV3 includes all features available in the PremiumV2 tier.

Multiple VM sizes are available for this tier, including 4-to-1 and 8-to-1 memory-to-core ratios:

For PremiumV3 pricing information, see App Service pricing.

To get started with the PremiumV3 pricing tier, see Configure PremiumV3 tier for Azure App Service.

Considerations for running and scaling an app

In the Free and Shared tiers, an app receives CPU minutes on a shared VM instance and can't scale out.

In other tiers, an app runs and scales as follows:

• When you create an app in App Service, it's part of an App Service plan. When the app runs, it runs on all the VM instances configured in the App Service plan.
• If multiple apps are in the same App Service plan, they all share the same VM instances.
• If you have multiple deployment slots for an app, all deployment slots also run on the same VM instances.
• If you enable diagnostic logs, perform backups, or run WebJobs, they also use CPU cycles and memory on these VM instances.

In this way, the App Service plan is the scale unit of the App Service apps. If the plan is configured to run five VM instances, then all apps in the plan run on all five instances. If the plan is configured for autoscaling, then all apps in the plan are scaled out together, based on the autoscale settings.

For more information on scaling out an app, see Get started with autoscale in Azure.

Cost of App Service plans

This section describes how App Service apps are billed. For detailed, region-specific pricing information, see App Service pricing.

Except for the Free tier, an App Service plan carries a charge on the compute resources that it uses:

• Shared tier: Each app receives a quota of CPU minutes, so each app is charged for the CPU quota.
• Dedicated compute tiers (Basic, Standard, Premium, PremiumV2, PremiumV3): The App Service plan defines the number of VM instances that the apps are scaled to, so each VM instance in the App Service plan is charged. These VM instances are charged the same, regardless of how many apps are running on them. To avoid unexpected charges, see Delete an App Service plan.
• IsolatedV2 tier: The App Service Environment defines the number of isolated workers that run your apps, and each worker is charged.

You aren't charged for using the App Service features that are available to you (for example, configuring custom domains, TLS/SSL certificates, deployment slots, or backups). The exceptions are:

• App Service domains: You pay when you purchase one in Azure and when you renew it each year.
• App Service certificates: You pay when you purchase one in Azure and when you renew it each year.
• IP-based TLS connections: There's an hourly charge for each IP-based TLS connection, but some Standard or higher tiers give you one IP-based TLS connection for free. Server Name Indication (SNI)-based TLS connections are free.

If you integrate App Service with another Azure service, you might need to consider charges from that service. For example, if you use Azure Traffic Manager to scale your app geographically, Traffic Manager also charges you based on your usage. To estimate your cross-services cost in Azure, see Pricing calculator.

Scaling for capabilities or features

You can scale your App Service plan up or down at any time. It's as simple as changing the pricing tier of the plan. You can choose a lower pricing tier at first, and then scale up later when you need more App Service features.

For example, you can start testing your web app in a Free-tier App Service plan and pay nothing. When you add your custom DNS name to the web app, just scale your plan up to the Shared tier. Later, when you want to create a TLS binding, scale your plan up to the Basic tier. When you want to have staging environments, scale up to the Standard tier. When you need more cores, memory, or storage, scale up to a bigger VM size in the same tier.

The same process works in reverse. When you no longer need the capabilities or features of a higher tier, you can scale down to a lower tier and save money.

For more information on scaling up an App Service plan, see Scale up an app in Azure App Service.

If your app is in the same App Service plan with other apps, you might want to improve the app's performance by isolating the compute resources. You can isolate the resources by moving the app to a separate App Service plan.

Decision to use a new plan or an existing plan for an app

Because you pay for the computing resources that your App Service plan allocates (as described in the earlier section about cost), you can potentially save money by putting multiple apps into one App Service plan. You can continue to add apps to an existing plan as long as the plan has enough resources to handle the load.

However, keep in mind that apps in the same App Service plan all share the same compute resources. To determine whether the new app has the necessary resources, you need to understand the capacity of the existing App Service plan, along with the expected load for the new app. Overloading an App Service plan can potentially cause downtime for your new and existing apps. You can find more comparisons between plans at App Service limits.

Isolate your app in a new App Service plan when:

• The app is resource intensive.
• You want to scale the app independently from the other apps in the existing plan.
• The app needs resources in a different geographical region. This way, you can allocate a new set of resources for your app and gain greater control of your apps.

Related content

• Manage an App Service plan