How do Amazon EC2 Reserved Instances that are size-flexible apply to my AWS bill?

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I want to know how my Amazon Elastic Compute Cloud (Amazon EC2) Reserved Instances (RIs) apply to my AWS bill if the Reserved Instances are size-flexible.


To find out if your RI is size-flexible, see How can I find out if my Amazon EC2 Reserved Instance provides regional benefit or size flexibility?

Size-flexible RIs apply to any usage in a particular instance family. Here are a few examples of how that can work in practice:

  • Your RI applies to any instance in its family of its same size or smaller. For example, if you purchase an RI for an m3.large instance, the RI also applies to m3.medium instances.
  • Multiple smaller RIs combine to apply to larger instances. For example, if you purchase two RIs for two m3.medium instances, these RIs also apply to an m3.large instance.

For more examples, see How Reserved Instances are applied.

RIs apply automatically to your billing. You can't choose which specific instances receive the benefit of your RIs.

If you're in an organization with multiple accounts under a consolidated bill, additional considerations can apply. For more information, see How is the pricing benefit of a Reserved Instance applied across an organization's consolidated bill?

Related information

Analyzing your costs with Cost Explorer

Amazon EC2 usage reports

AWS OFFICIALUpdated 3 years ago