AWS List Price Per Month vs Projected Cost

Products

• CloudHealth

Issue/Introduction

The term "List Price Per Month" is the List Price per Month is pulled directly from Amazon and It is their stated list price.

However, the Projected Cost is calculated through linear extrapolation:
(Actual MTD cost) + [(Average daily cost based on the last 31 days) x (Remaining days in the month)]
As such, the Projected Cost is merely a guide that becomes more accurate as the month progresses and more actual MTD data is available.

Resolution

The Total EC2 Cost and the Total EBS cost to use for projection:
Total Cost = EC2 Total Cost + EBS Total Cost
EC2 Total cost = EC2 Compute cost + EC2 Transfer Cost
EBS Total Cost = EBS Storage Cost + EBS PIOPS Cost + EBS I/O Costs 

Additional Information

The "list price per month" for an AWS EC2 instance typically does not include the cost of EBS.

The "list price per month" for an AWS EC2 instance is composed of several key components that can cause price differences even for the same instance type:

• Instance Usage and Type: The base cost depends on the instance type, which includes factors like number of vCPUs, memory size, and workload optimization (e.g., compute-optimized, memory-optimized). More powerful instances cost more per hour.
• Pricing Model: AWS offers multiple pricing models that affect the monthly cost:

• On-Demand: Pay per hour or second with no upfront commitment, typically the highest price.
• Reserved Instances or Savings Plans: Require 1- or 3-year commitments for significant discounts.
• Spot Instances: Use spare capacity at up to 90% discount but with interruption risk.

• Operating System and Licensing: Prices vary by OS (Linux, Windows, RHEL, SLES) and whether software licenses are included or brought by the user. Windows and RHEL licenses add to the cost.
• Region and Availability Zone: Pricing differs by AWS region due to infrastructure costs and demand. For example, the same instance type costs more in EU (Ireland) than US West (Oregon).
• Additional Fees:

• Dedicated Instances add a per-region fee plus hourly instance fees.
• Elastic IP addresses, detailed monitoring, and load balancing can add to monthly costs.
• Storage (EBS volumes) and data transfer costs are separate but contribute to total monthly charges.

• Instance Size Variations: Even within the same instance family, different sizes (e.g., t3.medium vs t3.large) have different prices proportional to their resources.

In summary, the "list price per month" is a function of the instance type and size, pricing model chosen, operating system licensing, AWS region, and any additional services or features used alongside the instance. This explains why instances of the same type may have different list prices per month