On-Demand Instances - Amazon Elastic Compute Cloud

On-Demand Instances

With On-Demand Instances, you pay for compute capacity by the second with no long-term commitments. You have full control over its lifecycle—you decide when to launch, stop, hibernate, start, reboot, or terminate it.

There is no long-term commitment required when you purchase On-Demand Instances. You pay only for the seconds that your On-Demand Instances are in the running state, with a 60-second minimum. The price per second for a running On-Demand Instance is fixed, and is listed on the Amazon EC2 Pricing, On-Demand Pricing page.

We recommend that you use On-Demand Instances for applications with short-term, irregular workloads that cannot be interrupted.

For significant savings over On-Demand Instances, use AWS Savings Plans, Spot Instances, or Reserved Instances.

Work with On-Demand Instances

You can work with On-Demand Instances in the following ways:

If you're new to Amazon EC2, see How to get started with Amazon EC2.

On-Demand Instance limits

There is a limit on the number of running On-Demand Instances per AWS account per Region. On-Demand Instance limits are managed in terms of the number of virtual central processing units (vCPUs) that your running On-Demand Instances are using, regardless of the instance type.

We provide the following limits for On-Demand Instances:

  • Running On-Demand DL instances

  • Running On-Demand F instances

  • Running On-Demand G and VT instances

  • Running On-Demand High Memory instances

  • Running On-Demand HPC instances

  • Running On-Demand Inf instances

  • Running On-Demand P instances

  • Running On-Demand Standard (A, C, D, H, I, M, R, T, Z) instances

  • Running On-Demand Trn instances

  • Running On-Demand X instances

Each limit specifies the vCPU limit for one or more instance families. For information about the different instance families, generations, and sizes, see Amazon EC2 Instance Types.

You can launch any combination of instance types that meet your changing application needs, as long as the number of vCPUs does not exceed your account limit. For example, with a Standard instance limit of 256 vCPUs, you could launch 32 m5.2xlarge instances (32 x 8 vCPUs) or 16 c5.4xlarge instances (16 x 16 vCPUs). For more information, see EC2 On-Demand Instance limits.

Monitor On-Demand Instance limits and usage

You can view and manage your On-Demand Instance limits using the following methods.

To view your current limits using the Amazon EC2 console
  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

  2. From the navigation bar, select a Region.

  3. From the navigation pane, choose Limits.

  4. Select Running instances from the first filter. The Current limit column displays the maximum number of vCPUs for each On-Demand Instance instance type for your account.

To view your current limits using the Service Quotas console
  1. Open the Service Quotas console at https://console.aws.amazon.com/servicequotas/home/services/ec2/quotas/.

  2. From the navigation bar, select a Region.

  3. In the search bar, enter On-Demand.

  4. The Applied quota value column displays the maximum number of vCPUs for each On-Demand Instance instance type for your account.

To view your current limits using the AWS Trusted Advisor console

Open Service limits page in the AWS Trusted Advisor console.

To configure CloudWatch alarms

With Amazon CloudWatch metrics integration, you can monitor your EC2 usage against your limits. You can also configure alarms to warn about approaching limits. For more information, see Service Quotas and Amazon CloudWatch alarms in the Service Quotas User Guide.

Calculate how many vCPUs you need

You can use the vCPU limits calculator to determine the number of vCPUs that you require for your application needs.

When using the calculator, keep the following in mind: The calculator assumes that you have reached your current limit. The value that you enter for Instance count is the number of instances that you need to launch in addition to what is permitted by your current limit. The calculator adds your current limit to the Instance count to arrive at a new limit.

You can view and use the following controls and information:

  • Instance type – The instance types that you add to the vCPU limits calculator.

  • Instance count – The number of instances that you require for the selected instance type.

  • vCPU count – The number of vCPUs that corresponds to the Instance count.

  • Current limit – Your current limit for the limit type to which the instance type belongs. The limit applies to all instance types of the same limit type. For example, in the preceding screenshot, the current limit for m5.2xlarge and c5.4xlarge is 2,016 vCPUs, which is the limit for all the instance types that belong to the All Standard instances limit.

  • New limit – The new limit, in number of vCPUs, which is calculated by adding vCPU count and Current limit.

  • X – Choose the X to remove the row.

  • Add instance type – Choose Add instance type to add another instance type to the calculator.

  • Limits calculation – Displays the current limit, vCPUs needed, and new limit for the limit types.

    • Instance limit name – The limit type for the instance types that you selected.

    • Current limit – The current limit for the limit type.

    • vCPUs needed – The number of vCPUs that corresponds to the number of instances that you specified in Instance count. For the All Standard instances limit type, the vCPUs needed is calculated by adding the values for vCPU count for all the instance types of this limit type.

    • New limit – The new limit is calculated by adding Current limit and vCPUs needed.

    • Options – Choose Request limit increase to request a limit increase for the corresponding limit type.

To calculate the number of required vCPUs
  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

  2. From the navigation bar, select a Region.

  3. From the left navigator, choose Limits.

  4. Choose Calculate vCPU limit.

  5. Choose Add instance type, choose the required instance type, and specify the required number of instances. To add more instance types, choose Add instance type again.

  6. View the Limits calculation pane for the new limit required for the specified instances.

  7. When you've finished using the calculator, you can choose Request on-demand limit increase or Close.

Request a limit increase

Even though Amazon EC2 automatically increases your On-Demand Instance limits based on your usage, you can request a limit increase if necessary. For example, if you intend to launch more instances than your current limit allows, you can request a limit increase using the Limits Calculator, as described in the previous section, or using one of the methods described in Amazon EC2 service quotas.

Query the prices of On-Demand Instances

You can use the Price List Service API or the AWS Price List API to query the prices of On-Demand Instances. For more information, see Using the AWS Price List API in the AWS Billing User Guide.