Amazon EC2 Reserved Instances and Other AWS Service Reservation Models
AWS Whitepaper

AWS Cost and Usage Report

The AWS Cost and Usage Report contains the most comprehensive set of data about your AWS costs and usage, including additional information regarding AWS services, pricing, and reservations. By using the AWS Cost and Usage report, you can gain a wealth of reservation-related insights about the Amazon Resource Name (ARN) for a reservation, the number of reservations, the number of units per reservation, and more. It can help you do the following:

  • Calculate savings – Each hourly line item of usage contains the discounted rate that was charged, as well as the public On-Demand rate for that usage type at that time. You can quantify your savings by calculating the difference between the public On-Demand rates and the rates you were charged.

  • Track the allocation of Reserved Instance discounts – Each line item of usage that receives a discount contains information about where the discount came from. This makes it easier to trace which instances are benefitting from specific reservations.

These reports update up to three times per day.

Reserved Instances on Your Cost and Usage Report

The Fee line item is added to your bill when you purchase an All Upfront or Partial Upfront Reserved Instance, as shown.

The RI Fee line item describes the recurring monthly charges that are associated with Partial Upfront and No Upfront Reserved Instances. The RI Fee is calculated by multiplying your discounted hourly rate by the number of hours in the month, as shown.

The Discounted Usage line item describes the instance usage that received a matching Reserved Instance discount benefit. It’s added to your bill when you have usage that matches one of your Reserved Instances, as shown.