EC2 Instances Purchasing Options

On-Demand Instances

• Usage: Short workloads, unpredictable application behavior
• Pricing: Pay by the second (Linux/Windows after the first minute) or by the hour (other OS)
• Cost: Highest cost, no upfront payments, no long-term commitments
• Flexibility: High, no commitment

Reserved Instances

• Usage: Long workloads (e.g., databases)
• Term: 1 or 3 years
• Discounts: Up to 72% compared to on-demand
• Payment Options: Upfront, Partial Upfront, No Upfront (more upfront payment yields higher discounts)
• Flexibility: Specific instance attributes (type, region, tenancy, OS)
• Scope: Region or a specific Availability Zone (AZ)
• Marketplace: Option to buy/sell reserved instances

Convertible Reserved Instances

• Flexibility: Change instance type, family, OS, scope, tenancy
• Discounts: Up to 66% compared to on-demand

Savings Plans

• Term: 1 or 3 years
• Commitment: Specific amount of usage in dollars