Understanding your reservation line items
RIs provide you a significant discount compared to On-Demand Instance pricing. RIs aren't physical instances. They're a billing discount applied to the use of On-Demand Instances in your account. These On-Demand Instances must match certain attributes to benefit from the billing discount.
Topics
In the following tables, the columns and rows from AWS CUR are transposed for clarity. The values in the first column represent the headers of a report. These examples include only a few key AWS CUR columns. To learn more about other AWS CUR columns, see the Data dictionary.
Upfront fee
The Fee line item is added to your bill when you purchase
an All Upfront or Partial Upfront RI.
The following table shows how this one-time fee appears in some AWS CUR columns.
| lineItem/LineItemType | Fee |
| lineItem/ProductCode | AmazonEC2 |
| lineItem/UsageStartDate | 2016-01-01T00:00:00Z |
| lineItem/description | Sign up charge for subscription: 363836886, planId: 1026576 |
| lineItem/UnblendedCost | 68 |
| Reservation/ReservationARN | arn:aws:ec2:us-east-1:123456789012:reserved-instances/f8c204c1-dd48-43f1-adb8-f88aa61e0dea |
True-up fee
If you exchange a Convertible Reserved Instance, any cost associated with the exchange of the original Reserved Instance and the new Reserved instance (true-up fee) is also added to your bill as a Fee line item. For a true-up fee, the reservation/ReservationARN column contains reserved-instance-exchange/riex.
The following table shows a true-up fee from exchanging a Convertible Reserved Instance.
| lineItem/ LineItemType | lineItem/ ProductCode | lineItem/ UsageStartDate | lineItem/ description | lineItem/ UnblendedCost | Reservation/ ReservationARN |
|---|---|---|---|---|---|
| Fee | AmazonEC2 | 2016-01-01T00:00:00Z | arn:aws:ec2:eu-west-1:012345678901:reserved-instance-exchange/riex-examplef-5d71-4215-886f-17a3f64ea972 |
Recurring monthly RI fee
The RI Fee line item describes the recurring monthly charges that are associated RIs applied that month. The RI Fee initially is added to your bill on the day of purchase and on the first day of each billing period thereafter.
The RI Fee is calculated by multiplying your discounted hourly rate and the number of hours in the month.
The following table shows how the recurring monthly charges appear in the report.
| lineItem/LineItemType | RI fee |
| lineItem/ProductCode | AmazonEC2 |
| lineItem/UsageStartDate | 2016-01-01T00:00:00Z |
| lineItem/UsageType | HeavyUsage: m4.large |
| lineItem/description | USD 0.0309 hourly fee per Linux/UNIX (Amazon VPC), m4.large instance |
| lineItem/ normalization factor | 4 |
| lineItem/UnblendedCost | 23 |
| Reservation/AvailabilityZone | |
| Reservation/ReservationARN | arn:aws:ec2:us-east-1:123456789012:reserved-instances/f8c204c1-dd48-43f1-adb8-f88aa61e0dea |
| Reservation/TotalReservedunits | 744 |
| Reservation/TotalReservedNormalizedUnits | 2976 |
Recurring monthly charges are recorded differently for RIs that have an Availability Zone or AWS Region Region scope. For RIs that have an Availability Zone scope, the corresponding Availability Zone is shown in the reservation/AvailabilityZone column. For RIs that have a Region scope, the reservation/AvailabilityZone column is empty. RIs with a Region scope have values for the lineitem/NormalizationFactor and reservation/TotalReservedNormalizedUnits columns that show the instance size.
The recurring RI fee is calculated differently than the SavingsPlanRecurringFee. The recurring RI fee is a monthly charge while the SavingsPlanRecurringFee is an hourly charge. For information on the SavingsPlanRecurringFee, see Understanding Savings Plans.
RI discount benefits
The Discounted Usage line item describes the instance usage that received a matching RI discount benefit, and is added to your bill when you have usage that matches one of your RIs. AWS calculates RI discount benefits based on matching usage: for example, the use of an instance that matches the instance reservation. If you have matching usage, the cost associated with the usage line item is always zero because the charges associated with RIs are already accounted for in the two other line items (the upfront fee and the recurring monthly charges).
The following table shows an example of usage that received an RI discount benefit.
| lineItem/LineItemType | DiscountedUsage |
| lineItem/ProductCode | AmazonEC2 |
| lineItem/UsageStartDate | 2016-01-01T00:00:00Z |
| lineItem/UsageType | BoxUsage:m4.large |
| lineItem/description | Linux/UNIX (Amazon VPC), m4.large Reserved Instance applied |
| lineItem/ResourceID | i-1bd250bc |
| lineItem/AvailabilityZone | us-east-1b |
| lineItem/normalizationfactor | 4 |
| lineItem/NormalizedUsageAmount | 4 |
| lineItem/UnblendedRate | 0 |
| lineItem/UnblendedCost | 0 |
| Reservation/ReservationARN | arn:aws:ec2:us-east-1:123456789012:reserved-instances/f8c204c1-dd48-43f1-adb8-f88aa61e0dea |
The value for UsageAmount in the Amazon EC2 DiscountedUsage line is the actual number of hours used. The value for NormalizedUsageAmount is the value for UsageAmount multiplied by the value for NormalizationFactor. The value for NormalizationFactor is determined by the instance size. When an RI benefit discount is applied to a matching line item of usage, the Amazon Resource Name (ARN) value in the reservation/ReservationARN column for the initial upfront fees and recurring monthly charges matches the ARN value in the discounted usage line items.
For more information about mapping instance size to normalization factor, see Support for modifying instance sizes in the Amazon EC2 User Guide for Linux Instances.
Reserved Instance type
To determine if your report line items are associated with a Standard Reserved Instance or a Convertible Reserved Instance, filter the lineItem/LineItemType column by Fee or RI fee. Then, review the product/OfferingClass column, which indicates the Reserved Instance type.
The following table shows a Fee line item from a Standard Reserved Instance:
The following table shows an RI fee line item from a Convertible Reserved Instance:
To determine if your report line items are associated with a zonal or regional Reserved Instance, review the reservation/AvailabilityZone column. For zonal Reserved Instances, this column shows the corresponding Availability Zone. For regional Reserved Instances, this column is empty.
Reserved Instance benefits applied to instance usage
To understand which instance usage line items benefitted from which Reserved Instances, you can filter your report by one or more of the following columns:
reservation/reservationARN: Filter this column by a reservation ARN to identify which Reserved Instance lease is associated with each line item.
lineitem/ResourceId: Review this column for the ID of the resource that's covered by the Reserved Instance.
lineitem/LineItemType: Filter this column by Fee, RI fee, or DiscountedUsage to determine the associated fees or benefits.
lineitem/UsageType: Filter this column by HeavyUsage to identify RI fee line items. Or, filter this column by BoxUsage to identify DiscountedUsage line items.
lineitem/UsageAmount: For RI fee line items, this column shows the total number of hours in the month that the Reserved Instance was applied. For DiscountedUsage line items, this column shows the total number of hours that the Reserved Instance was applied to a specific instance at the daily or monthly level, depending on how you configured your report.
To understand a size flexible Reserved Instance’s number of normalized units applied to instance usage, review the lineitem/NormalizedUsageAmount column in your report. The value in this column equals the product of the following columns:
lineitem/UsageAmount: This column shows the metered instance usage measured in hours.
lineItem/NormalizationFactor: For DiscountedUsage and RI fee line items, this column shows the associated normalization factor of the instance. For more information on the normalization factor, see Instance size flexibility determined by normalization factor in the Amazon EC2 User Guide for Linux Instances.
For AWS Organizations with multiple accounts, to see which accounts purchased or benefitted from a Reserved Instance, review the following columns:
reservation/reservationARN: Review the reservation ARNs to see which accounts purchased the Reserved Instance. The ARN includes the account ID.
lineitem/UsageAccountID: For DiscountedUsage line items, this column identifies the account IDs that received benefits from the purchased Reserved Instances.
A Reserved Instance is a billing subscription and not a resource like an Amazon EC2 instance. Because of this, Reserved Instances that are tagged don't populate line items like a tagged resource. For line items with DiscountedUsage, tags populate for the tagged resources and not for the Reserved Instance.
To identify costs associated with a specific Reserved Instance lease, you can filter Fee or RI fee line items by the Reserved Instance ARN, which is the lease ID. To organize your cost data for Reserved Instances, consider using AWS Cost Categories. For more information, see Managing your costs with AWS Cost Categories in the AWS Billing User Guide
