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How do I modify a Reserved Instance or apply Reserved Instance benefits to existing EC2 instances?

2 minute read

I want to change my existing Amazon Elastic Compute Cloud (Amazon EC2) instance to a Reserved Instance or modify my existing Reserved Instance.

Resolution

Modify an existing Reserved Instance

Prerequisite: Make sure that you adhere to the modification requirements.

Use the Amazon EC2 console to modify your existing Reserved Instance. You can modify the instance size of only Linux and UNIX Reserved Instances that don't have a specific license. You can't modify the size of Reserved Instances for Windows, Red Hat Enterprise Linux (RHEL), or SUSE Linux.

Note: If the Modify Reserved Instances option isn't available (greyed out), then your Reserved Instance isn't in an Active state, or you can't modify it. As a workaround, you can sell Standard Reserved Instances in the Amazon EC2 Reserved Instance Marketplace.

If you have a Convertible Reserved Instance, then you can exchange it for another Convertible Reserved Instance with a different configuration.

Apply Reserved Instances benefits to existing instances

You can't convert a running On-Demand Instance into a Reserved Instance. Instead, purchase a Reserved Instance that matches your existing On-Demand Instance attributes, such as instance type, platform, tenancy, and Availability Zone. Then, AWS automatically applies the Reserved Instance discount to the relevant On-Demand Instance.

For example, if you have a running m5.xlarge EC2 Windows instance in the us-east-1f Availability Zone, then the Reserved Instance must also be a m5.xlarge Windows instance in us-east-1f.

The Reserved Instance status might be in the Pending state immediately after purchase. Within a few minutes for the state to change to Active to confirm that you completed the transaction. To view the Reserved Instance expiration date, check Expires information under Instance details.

Note: Reserved Instances are billing constructs. They don't create or modify running instances. Instead, they apply automatic billing discounts to On-Demand Instances that match.