Compute Savings Plans vs EC2 Instance Savings Plans: flexibility vs depth

Quick answer

Compute Savings Plans are the flexible option — up to ~66% off across any family, region, OS, plus Fargate and Lambda. EC2 Instance Savings Plans give a deeper ~72% but lock to one family in one region. Both commit an hourly dollar amount for 1-3 years. Default to Compute SPs for flexibility; pick EC2 Instance SPs for a stable, known fleet where the extra discount is worth the rigidity.

Once you've decided Savings Plans over Reserved Instances (see Reserved Instances vs Savings Plans), there's a second choice: which Savings Plan. The two types trade the same currency every commitment does — discount depth versus flexibility.

Compute Savings Plans: flexible

Up to ~66% off, applied automatically to matching usage regardless of instance family, size, region, OS, or tenancy — and crucially, across EC2, Fargate, and Lambda. Resize, switch families, move regions, or shift from VMs to containers and the discount follows your spend. The flexible default for most teams.

EC2 Instance Savings Plans: deeper, narrower

Up to ~72% off — a few points more — but committed to a specific instance family in a specific region. You can change size within the family and OS, but leave the family or region and the plan no longer applies. The right pick when you run a stable, known fleet you're confident won't move.

How to choose

Compute SP: shifting workloads, multiple families, Fargate/Lambda in the mix, or uncertainty about future architecture.
EC2 Instance SP: a steady, predictable family in one region where you want the maximum discount.
Both: an EC2 Instance SP for the rock-stable core, a Compute SP layered on top for everything else.

Commit to baseline

Whichever type, commit to the steady hourly spend you reliably run — not the peak. Cover the baseline with the plan and let variable demand run on-demand or Spot. The Fargate angle matters here too: a Compute SP discounts your Fargate baseline alongside EC2.

FAQ

What's the difference between Compute Savings Plans and EC2 Instance Savings Plans?

Compute Savings Plans are the most flexible — up to ~66% off, applying across any instance family, size, region, OS, and tenancy, plus Fargate and Lambda. EC2 Instance Savings Plans give a deeper discount (up to ~72%) but lock you to a specific instance family in a specific region. You trade flexibility for a few extra points of discount.

Which Savings Plan should I choose?

Choose Compute Savings Plans if your usage shifts across families, regions, or includes Fargate/Lambda — the flexibility prevents stranded commitment. Choose EC2 Instance Savings Plans when you run a stable, known instance family in one region and want the maximum discount. Many teams use Compute SPs as the default for their adaptability.

How are Savings Plans different from Reserved Instances?

Both commit to 1 or 3 years for a discount, but Savings Plans commit to an hourly dollar amount (e.g. $10/hour) and apply automatically to matching usage, while Reserved Instances reserve specific instance configurations. Savings Plans are generally simpler to manage; see the dedicated comparison for the full picture.

Do Compute Savings Plans cover Fargate and Lambda?

Yes — that's a key advantage. Compute Savings Plans apply to EC2, Fargate, and Lambda usage, so a single commitment can discount your containers and serverless functions alongside VMs. EC2 Instance Savings Plans cover only EC2.

How much should I commit to?

Commit to your steady baseline hourly spend, not your peak. Look at the minimum compute you reliably run around the clock and cover that; let variable demand run on-demand or Spot. Over-committing strands money on an hourly rate you don't use.

How does C3X help size a Savings Plan?

C3X prices your EC2, Fargate, and Lambda resources at on-demand rates from your Terraform, giving you the baseline hourly spend figure to size a Compute or EC2 Instance Savings Plan against your actual fleet.

What to do next

Sizing any Savings Plan starts from a real baseline number. C3X prices your EC2, Fargate, and Lambda at on-demand rates from your Terraform, so you can size a Compute or EC2 Instance Savings Plan against the fleet you actually run. The quickstart runs it in minutes.