Why aren't my Amazon EC2 Reserved Instances applying to my AWS billing in the way that I expected?
Last updated: 2020-12-23
I purchased an Amazon Elastic Compute Cloud (Amazon EC2) Reserved Instance (RI), but it's being used in a way that I didn't expect.
If your RI isn't applying to any usage at all, see Why isn't my Reserved Instance applying to my AWS billing?
The most common reason that an RI discount isn't applying to the instance in the way that you expect is that the terms of the RI don't match any instances running on your account. The RI that you purchase must match the platform, type, size (or size footprint), Availability Zone (if applicable), and tenancy of a running On-Demand Instance for it to apply. Check the terms of your RI and the instance it applies to.
If your RI is active and matches the specifications of a running On-Demand Instance, then use Cost Explorer to analyze your spending and usage. You can use AWS Cost Explorer to generate the RI Utilization and RI coverage reports. For more information, see How do I view my Reserved Instance utilization and coverage?
If the RI terms do match the instance that you intended it to apply to, consider the following:
- RI discounts are applied differently in an organization's consolidated bill, depending on whether RI sharing is turned on or off. For more information, see How is the pricing benefit of a Reserved Instance applied across an organization's consolidated bill?
- For size-flexible RIs, the billing benefit isn't necessarily applied to an instance exactly matching the terms of the RI before it matches a complementary grouping of smaller instances. For example, if you run an m3.large instance and two m3.medium instances, and you purchase a Reserved Instance for an m3.large instance, the RI billing benefit might apply to either of these groups of instances. To see which instances are covered by RIs on your account, use one of the bill reporting options here: How do I find out if my Amazon EC2 Reserved Instances are being fully used?