Use AWS Compute Optimizer and Cost Optimization Hub to surface likely idle resources, then verify each candidate in Trusted Advisor, Cost Explorer, and with the workload owner before changing anything. The tools can show resource-level estimated savings, but there is no universal dollar figure: the cost depends on your account’s resources, regions, configuration, usage, pricing, discounts, and commitments.
Which AWS tools can find likely idle resources?
Start with AWS’s native recommendations and billing views. They provide useful leads, but they do not form a complete inventory of every resource that may be unnecessary. Coverage and eligibility vary by resource type, metrics, and account setup.
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Compute Optimizer
AWS describes Compute Optimizer as analyzing resource configurations and utilization metrics to identify idle resources and make rightsizing recommendations. It supports multiple resource types and offers console and API access. Recommendations can cover multiple Regions; organization-wide recommendations require the management account to opt in. See the Compute Optimizer User Guide.
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Cost Optimization Hub
Cost Optimization Hub consolidates recommendations across accounts and Regions. Its recommendations include idle-resource deletion and rightsizing, but also options such as Savings Plans and Reserved Instances; not every item represents an idle resource. AWS says its savings estimates account for commercial terms such as active commitments and deduplicate related opportunities. Review Cost Optimization Hub.
Trusted Advisor
Trusted Advisor offers resource-specific checks, including underutilized EBS volumes and cost optimization checks that use Cost Optimization Hub and Compute Optimizer. AWS says the newer checks refresh several times daily, though a change can take a few hours to appear. Check current console eligibility and access requirements rather than assuming every account sees every check. See AWS Trusted Advisor.
Cost Explorer Resource Optimization
AWS’s pricing guidance says Cost Explorer’s Resource Optimization report can identify EC2 instances that are idle or have low utilization, with suggested actions such as stopping or downsizing. AWS discusses EBS, RDS, Redshift, and load balancer opportunities separately; the EC2 report alone is not a detector for all AWS waste. See AWS cost optimization guidance.
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How to run a useful review
- Set the scope. Choose the account or organization, Regions, and review period. For fleet-wide visibility, confirm the organization opt-in and permissions needed by the AWS tools.
- Enable recommendations and billing data. Opt in to Compute Optimizer and ensure Cost Explorer is enabled if you want its billing data used for savings calculations and pricing information.
- Collect candidates. Review Compute Optimizer and Cost Optimization Hub first, then use relevant Trusted Advisor checks and Cost Explorer Resource Optimization to add supporting evidence.
- Inspect each resource. Record its identifier, Region, recommendation, utilization history, estimated monthly cost, estimated savings, and any performance-risk indication shown by AWS.
- Confirm ownership and purpose. Find the service or team responsible and check for dependencies, standby or recovery duties, seasonal use, compliance retention, and planned changes.
- Choose a reversible action where possible. Stop or downsize a compute resource before deleting it when that is operationally safe; snapshot data before removing storage that may need recovery.
- Measure the outcome. Record the action date and owner, then check workload health and subsequent billing data to distinguish realized savings from the original estimate.
What AWS means by “idle” depends on the resource
A recommendation reflects a defined metric window and eligibility rule, not a universal definition of waste. AWS’s cited Trusted Advisor criteria illustrate why the resource type matters.
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| Resource or check | AWS criterion or eligibility | How to interpret it |
|---|---|---|
| Underutilized EBS volume in Trusted Advisor | Unattached, or less than 1 IOPS per day over the past 7 days, under the cited check. | This is that check’s signal, not proof that the volume contains disposable data. |
| Inactive NAT Gateway in Trusted Advisor | 0 bytes processed in the previous 30 days under the cited check. | AWS warns that NAT Gateways incur hourly and data-processing charges, so an unused gateway can still cost money. |
| EC2 instances and Auto Scaling groups in Compute Optimizer | At least 30 hours of CloudWatch metric data in the past 14 days are required for the cited recommendations. | Insufficient metrics may mean no recommendation appears; it does not establish that the resource is in use. |
| Unattached EBS volume in Compute Optimizer | AWS documents a snapshot-and-delete recommended action when the volume has been unattached from EC2 instances for 32 or more days. | Apply the recommendation only after checking ownership, retention needs, and recovery requirements. |
These figures are AWS’s resource-specific criteria, not universal idle thresholds. Compute Optimizer has additional resource-specific metric requirements; consult its requirements documentation. Cost Explorer must be enabled for Compute Optimizer to use billing data in savings calculations and populate pricing information.
How much do unused resources cost?
The amount is account-specific. AWS recommendation views can show estimated resource-level savings, but a recommendation is not a bill and its estimate is not a promise of realized savings. The estimate depends on the resource, Region, configuration, usage, applicable pricing, and discounts or commitments.
Do not add every displayed opportunity together without checking for overlap. AWS cautions that total savings opportunity may not equal the sum of idle, rightsizing, and license savings figures. Cost Optimization Hub deduplicates related opportunities and accounts for commercial terms, but estimates from different recommendation categories or tools should not be treated as directly comparable unless their assumptions are known. See AWS’s explanation of Cost Optimization Hub estimates.
Validate the workload before taking action
Before stopping, resizing, or deleting anything, establish whether the resource is genuinely unused and what could break if it changes.
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- Ownership: identify the team, application, or account owner; investigate tags and deployment records where available.
- Workload role: check for disaster recovery, failover, backup, seasonal, batch, or compliance functions that may not show steady activity.
- Dependencies: inspect network paths, attached storage, DNS or routing references, monitoring, automation, and services that expect the resource to exist.
- History and risk: examine utilization over an appropriate period and consider AWS’s displayed performance risk, not only the latest low-usage signal.
- Data and recovery: confirm retention obligations and whether a snapshot or other recovery point is required before deleting storage.
- Cost context: distinguish avoidable recurring charges from charges affected by commitments, discounts, or other pricing terms.
For a qualifying unattached EBS volume, Compute Optimizer’s documented recommended action is to snapshot the volume before deleting it. That is a safer path to evaluate than treating every unattached volume as disposable; consult AWS’s EBS volume recommendations.
When third-party FinOps tools may help
A third-party platform may be useful if your team needs additional cost allocation, dashboards, or workflow across teams after establishing the AWS-native baseline. Vantage describes AWS cost visibility, recommendations, and automated remediation, and says its AWS integration uses a read-only cross-account IAM role: Vantage’s AWS integration. CloudZero describes resource-level AWS recommendations with estimated savings and guidance: CloudZero’s AWS cost optimization overview.
Those are vendor descriptions, not independent comparative tests. They do not establish that either platform finds more waste than AWS or guarantees savings.
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