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How It Works
When you purchase a Standard Reserved Instance, you commit to a specific EC2 instance type, region, operating system, and tenancy for either one or three years. AWS then applies a discounted rate to any matching on-demand usage during that term. The discount is calculated based on the configuration you select upfront and does not flex to cover different instance types or families. If your workload runs a consistent, predictable configuration throughout the term, the full discount applies. If the workload changes, the commitment continues billing at the reserved rate regardless of whether the usage matches.
Why It Matters for Cloud Cost
Standard Reserved Instances deliver the highest possible discount AWS offers on EC2 compute, up to 72% off on-demand pricing. That makes them attractive for stable, long-running workloads. The trade-off is rigidity. Because the commitment is locked to a specific configuration, any change in instance type, region, or operating system leaves the reservation unused. Unused Standard Reserved Instances continue to accrue charges with no offsetting benefit, making configuration drift and workload changes a direct financial liability. Teams that cannot predict usage 12 to 36 months in advance face meaningful risk of paying for capacity they cannot use.
Usage AI’s Autopilot mode purchases and adjusts commitments daily across AWS, GCP, and Azure without human approval, so commitment coverage stays current without manual intervention.