AWS Cloud Financial Management

Launch: Resource Optimization Recommendations

September 8, 2021: Amazon Elasticsearch Service has been renamed to Amazon OpenSearch Service. See details.

AWS now generates custom Amazon EC2 resource optimization recommendations, calculating ideal configurations based on your past usage. Using these recommendations in the AWS Cost Management product suite, you can identify opportunities for cost efficiency and act on them by terminating idle instances and rightsizing under-used instances. You can find these recommendations on the new, unified Recommendations summary page.

This post provides an overview of how to start using your resource optimization recommendations.

Accessing and using the new Recommendations summary page

You can find your resource optimization recommendations in the AWS Cost Management product suite. In the left navigation pane, choose Recommendations. Please note that you may not see this option if you are not yet opted into AWS Cost Explorer.

The Recommendations summary page provides an overview of all AWS-generated recommendations, including the new resource optimization recommendations and the existing AWS reservation purchase recommendations. The latter includes EC2, Amazon RDS, Amazon Redshift, Amazon OpenSearch Service (successor to Amazon Elasticsearch Service), and Amazon OpenSearch Service reservations.

This page also summarizes the following:

  • Number of optimization opportunities: The number of recommendations available based on your past usage.
  • Estimated monthly savings: The projected monthly savings associated with each of the recommendations provided.
  • Estimated savings (%): The approximate savings relative to your current instance costs, based on the recommendation list. AWS bases this calculation on the On-Demand Instance price, and so it may fluctuate from the prediction.

AWS Cost Optimization Recommendations


Using this information, you can identify potential savings across different aspects of your business and act accordingly.

Accessing and understanding your resource optimization recommendations

To access your recommendations, in the upper-right corner of the relevant table, choose View all. This takes you to the Resource Optimization subpage, which contains a full list of your EC2 instance-related recommendations. For master accounts, this view includes recommendations for all accounts in your organization.

These recommendations highlight cases where it may make sense to do one of the following:

  • Terminate idle instances
  • Rightsize underutilized instances

AWS Resource Optimization Recommendations

How do recommendations work?

Amazon EC2 generates instance recommendations by scanning your past usage over the previous 14 days. From there, AWS removes Spot Instance usage and any instances it believes that you terminated. AWS then analyzes the remaining instance usage to identify idle and underutilized instances:

  • Idle instances are instances that have lower than 1% maximum CPU utilization.
  • Underutilized instances are instances with maximum CPU utilization between 1% and 40%.

When an idle instance is detected, AWS generates a termination recommendation. When an underutilized instance is identified, AWS simulates covering that usage with a smaller instance within the same family. If bundling several smaller instance sizes within the same family could provide savings, AWS shows three rightsizing options. The AWS Recommendation shows a single step down in size to be conservative.

For each of these recommendations, AWS also provides the estimated savings monthly. These calculated potential savings include Reserved Instances. If moving to a smaller size would cost the customer more (in the case of a non-size flexible Reserved Instance), AWS automatically filters out those recommendations. The system only shows recommendations that result in positive cost savings.

Understanding your resource recommendations

The easiest way to get started is to adjust the recommendation parameters to return only idle instances identified. From there, you can modify the recommendation parameters to return recommendations for a set of tags, regions, or accounts and then act accordingly.

By default, Cost Management sorts recommendations by your estimated savings, letting you tackle the biggest savings first. To gain more insight into a specific recommendation, choose View.

The Recommendations Details page provides an overview of the resource details, resource utilization metrics, and purchase option (On-Demand or Reserved Instance) associated with that usage. It also includes a recommendation for either terminating or modifying the instance. To make those changes, choose Go to the Amazon EC2 console.

Resource Optimization Recommendation Detail

In the screenshot above, certain fields show no content. This is because I have not installed the Amazon CloudWatch agent. After it’s enabled, the CloudWatch agent monitors your resource usage at a granular level.

A few other things to note before you start:

  • Instance support: Recommendations supports all major EC2 instance families (C, M, T, R, X) but does not currently support GPU-based instances.
  • Reserved Instances: Recommendations takes size-flexible Reserved Instance logic into account when generating recommendations. This might create recommendations to down-size instances for $0 in direct savings, which ultimately frees Reserved Instance hours you can use to cover other underutilized resources.
  • Opt-in process: After you opt into Resource Optimization recommendations, it can take around 24 hours for your recommendations to be generated. The opt-in process happens at the master account level.
  • Access controls: The payer account controls which linked account can access Cost Explorer and Recommendations from the account settings page. IAM users with “ViewBilling” permissions can view these recommendations.

Sharing your cost optimization insights with others

From the Resource Optimization console, you can download a full or filtered list of your recommendations. From there, you can share a CSV of your recommendations or create a custom application using this data using the Cost Explorer API. This helps in sharing cost savings with other members of your organization, as well as fostering a cost-aware culture.


Resource optimization recommendations identify all available cost savings and rightsizing opportunities in your account or, for payer accounts, across your whole organization. Opportunities are identified even if they result in zero-dollar savings, as they might also improve your Reserved Instance coverage. Using these recommendations, you can enable members of your organization to easily identify and act on opportunities for improving cost efficiency.

To learn more about how to use Resource Optimization recommendations to optimize your costs, see the what’s new post and the Optimizing your Costs with Rightsizing Recommendations user guide.


Erin Carlson

Erin Carlson

Erin leads a team of designers who are laser-focused on enhancing the experience of accessing, analyzing, and optimizing AWS costs and usage. She also works with customers and field teams worldwide to provide product training and guidance around best practices for using the AWS Cost Management product portfolio. Erin was the Product Marketing Manager who first developed and oversaw the AWS Cost Management brand.