This post is contributed by Saloni Sonpal, Senior Product Manager, Amazon EC2

As an Amazon EC2 customer running On-Demand Instances, you can increase or decrease your compute capacity depending on your application’s needs, and only pay for what you use. EC2 implements instance limits, which give you a highly elastic experience while protecting you from unintentional spending or abuse.

To streamline launching On-Demand Instances, AWS is introducing simplified EC2 limits on September 24, 2019, based on the number of virtual central processing units (vCPUs) attached to your running instances. In addition to now measuring usage in number of vCPUs, there will only be five different On-Demand Instance limits—one limit that governs the usage of standard instance families such as A, C, D, H, I, M, R, T, and Z, and one limit per accelerated instance family for FPGA (F), graphic-intensive (G), general purpose GPU (P), and special memory optimized (X) instances. Use your limits in terms of the number of vCPUs for the EC2 instance types to launch any combination of instance types that meet your changing application needs. For example, with a Standard Instance Family limit of 256 vCPUs, you could launch 32 m5.2xlarge instances (32 x 8 vCPUs) or 16 c5.4xlarge instances (16 x 16 vCPUs) or any combination of applicable instance types and sizes that total 256 vCPUs. For more information on vCPU mapping for instance types, see Amazon EC2 Instance Types.

During a transition period from September 24, 2019, through October 24, 2019, you can opt in to receive vCPU-based instance limits. When you opt in, EC2 automatically computes your new limits, giving you access to launch at least the same number of instances (if not more) than you do currently. Beginning October 24, 2019, all accounts will switch to vCPU-based instance limits, and the current count-based instance limits will no longer be supported. Although the switchover will not impact your ability to launch EC2 instances, you should familiarize yourself with the new On-Demand Instance limits experience and opt into vCPU limits at a time of your choosing.

You can always view and manage your limits from the Limits page in the Amazon EC2 console and from the EC2 Service page in the Service Quotas console. With Amazon CloudWatch metrics integration, you can monitor EC2 usage against limits as well as configure alarms to warn about approaching limits. For more information, see EC2 On-Demand Instance limits. If you have any questions, contact the AWS support team on the community forums and via AWS Premium Support.