AWS sells two compute commitment vehicles. Reserved Instances cover EC2, RDS, ElastiCache, OpenSearch, and Redshift. Savings Plans cover EC2, Fargate, Lambda, and SageMaker. The right buyer side mix is laddered, not exclusive.
Reserved Instances and Savings Plans both trade a commitment for a discount. RIs cover compute, RDS, ElastiCache, OpenSearch, and Redshift. Savings Plans cover compute, Fargate, Lambda, and SageMaker. Each behaves differently inside the AWS billing engine.
This piece reads as a buyer side decision framework. Use it with the Compute Savings Plans deep dive, the EDP commitment calculator, the RI cost analysis piece, and the AWS pillar hub.
Reserved Instances are the legacy commitment model. AWS introduced Savings Plans in 2019 to simplify the family and region lock. The two vehicles now coexist because each covers a different part of the catalog.
The coverage map decides which vehicle fits the workload. The map is service driven, not workload driven. Treat the table below as the first cut for any commitment review.
| Service | Reserved Instance | Savings Plan |
|---|---|---|
| EC2 | Yes | Yes (Compute and EC2 Instance SP) |
| Fargate | No | Yes (Compute SP) |
| Lambda | No | Yes (Compute SP) |
| SageMaker | No | Yes (SageMaker SP) |
| RDS | Yes | No |
| ElastiCache | Yes | No |
| Redshift | Yes | No |
| OpenSearch | Yes | No |
Many enterprise teams discover the database coverage gap after they convert their compute estate to Savings Plans. RDS, ElastiCache, Redshift, and OpenSearch keep running at on demand rates until the team buys the matching RIs. The fix is to baseline the database spend and buy the RI portfolio at the same time as the Savings Plan ladder.
The headline discount ceilings differ. The realized discount also differs because the family flex of Savings Plans usually keeps coverage at 80 to 95 percent across the term, while locked Standard RIs sometimes drop to 60 to 75 percent.
| Vehicle | 1 year | 3 year |
|---|---|---|
| Standard RI all upfront | 40% | 72% |
| Convertible RI all upfront | 34% | 66% |
| EC2 Instance Savings Plan all upfront | 42% | 72% |
| Compute Savings Plan all upfront | 36% | 66% |
| RDS RI all upfront | 40% | 69% |
| ElastiCache RI all upfront | 35% | 55% |
The flexibility profile separates the two vehicles further. Standard RIs are locked. Convertible RIs allow family swaps. Savings Plans behave like a hourly commit that AWS allocates automatically.
Each vehicle wins on a different workload type. Match the workload to the vehicle and avoid mixing the two on the same line. The decision is service first, workload second.
The buyer side play is hybrid coverage. RIs cover the database services. Savings Plans cover the compute. The two layers behave independently inside the AWS billing engine.
| Layer | Vehicle | Target coverage |
|---|---|---|
| EC2 locked stack | EC2 Instance SP | 60 to 80 percent |
| EC2 dynamic stack | Compute SP | 40 to 60 percent |
| Fargate and Lambda | Compute SP | 50 to 80 percent |
| RDS stable clusters | Standard RI | 70 to 90 percent |
| ElastiCache stable nodes | Standard RI | 70 to 85 percent |
| Redshift production | Standard RI | 80 to 95 percent |
The eight step checklist below moves an AWS estate from a single vehicle posture into a layered, hybrid coverage plan. Open it at the next FinOps review.
No. Savings Plans cover EC2, Fargate, Lambda, and SageMaker. RDS, ElastiCache, Redshift, and OpenSearch are only covered by Reserved Instances. Enterprise estates that converted compute coverage to Savings Plans often discover the database coverage gap on the next monthly bill. The fix is to buy the matching RI portfolio at the same time as the Savings Plan ladder.
No. Savings Plans are not resellable on the AWS Marketplace. Standard Reserved Instances can be sold to other AWS customers through the Reserved Instance Marketplace. Convertible Reserved Instances and Savings Plans cannot. The marketplace resale value of Standard RIs is sometimes a relevant lever on locked production stacks where the workload pattern is uncertain.
Standard Reserved Instances reach 72 percent discount on a three year all upfront commitment. EC2 Instance Savings Plans match that ceiling on the same term. Compute Savings Plans top at 66 percent because of the family and region flexibility. The realized discount depends on the workload pattern, the family lock, and the term length.
No. Savings Plans are immutable. The plan covers an hourly USD spend rate for the term. AWS allocates the coverage automatically to the lines with the deepest discount. Customers cannot exchange a Savings Plan for a different one. The flexibility sits in the allocation engine, not in the commitment itself.
Standard RIs lock the instance family. Convertible RIs let the customer exchange the RI for a different family, size, or operating system inside the term. Standard RIs earn a higher discount ceiling. Convertible RIs trade discount for flexibility.
Both vehicles apply before the EDP discount. The EDP applies to net usage after Reserved Instance and Savings Plan coverage. Model the three layers together when sizing the EDP commit. SP and RI coverage reduce the spend that counts toward the EDP tier.
Redress runs the commitment review as part of the AWS FinOps and EDP renewal engagement. The work pulls the spend curve across compute and database services, models the layered allocation, and runs the net present value math. The deliverable is the hybrid coverage strategy and the residual commit map.
Read the related Vendor Shield, the Renewal Program, the Benchmark Program, the Software Spend Assessment, the Benchmarking framework, the about us page, the management team page, the locations page, and the contact page.
A buyer side framework for the next AWS Enterprise Discount Program renewal. Commit sizing, discount tier benchmarks, flexibility clauses, Savings Plan and Reserved Instance layering, marketplace pass through.
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