Explanation
Why the waste happens and who it affects.
When EC2 usage declines, shifts to different instance families, or moves to other services (e.g., containers or serverless), organizations may find that previously purchased Standard Reserved Instances or Savings Plans no longer match current workload patterns.
This misalignment results in underutilized commitments - where costs are still incurred, but no usage is benefiting from the associated discounts. Recovery options are limited: Standard RIs can be modified (Availability Zone, scope, and, for Linux/UNIX, instance size within the same family and generation), Convertible RIs can be exchanged, eligible Standard RIs can be sold on the RI Marketplace (lifetime limit of $50,000 or 5,000 RIs per account), and a Savings Plan with an hourly commitment of $100 or less can be returned only within seven days of purchase in the same calendar month. Beyond these options, the main path to recoup value is to steer workloads back toward the covered usage profile.
Billing model
The pricing dimensions that drive this cost.
- Standard RIs are billed hourly for a specific instance type, family, region, and tenancy
- Compute Savings Plans and EC2 Instance Savings Plans offer broader flexibility, but still require a minimum hourly usage commitment
- If actual usage falls below the commitment threshold, the difference is still billed, resulting in unused reservation charges
How to detect
4 checks to find it in your estate.
- Identify underutilized Standard Reserved Instances or Savings Plans by analyzing usage versus commitment
- Break down which instance families, sizes, or regions are covered but underused
- Map current workloads that were previously on those instance types - and investigate why they shifted away (e.g., scaling, performance, compatibility)
- Look for gaps between what was committed and how workloads have evolved to highlight mismatches
How to fix
4 ways to remove the waste.
- Review existing workloads to identify candidates that could migrate to the underutilized instance families
- For new or scaling workloads, prioritize launching on instance types that align with unused commitments
- Where possible, upgrade existing workloads to fit larger reserved types - while tracking the change to avoid overcommitment in future renewals
- Document any shifts made to accommodate current commitments and revisit those configurations once the reservation or plan term expires
Documentation
Vendor references for pricing and configuration.