What do I need to know before I purchase an Amazon EC2 Reserved Instance?

Resolution

Understand the contract length of a Reserved Instance

Reserved Instances have long contract terms of one or three years.

Reserved Instances are ideal if you can answer yes to the following questions:

• Will your workload run consistently for at least one year?
• Can you predict the specific EC2 instance type and size that you need?
• Is cost savings a priority over maximum flexibility?

Understand Reserved Instance billing

AWS bills most Reserved Instances as a lump sum each month for each hour in that month. You're charged for the established price whether you ran an instance that matched your reservation or not. Reserved Instances provide the maximum discount for instance types that you use often and for long periods of time.

Reserved Instance discounts might apply to AWS accounts in your organization's consolidated billing family. For more information, see How is the pricing benefit of a Reserved Instance applied across an organization's consolidated bill?

Understand capacity reservations

The scope of Reserved Instance is either by Availability Zone or by AWS Region. Capacity reservations apply only to zonal Reserved Instances, not Regional Reserved Instances.

To access capacity reservations without a billing discount, it's a best practice to use On-Demand Capacity Reservations instead of Reserved Instances. For short-term discounts on instances, launch a Spot Instance.

Purchase a Reserved Instance

To purchase a Reserved Instance, see How do I purchase an Amazon EC2 Reserved Instance?

For pricing information, see Amazon EC2 Reserved Instances pricing.

After the reservation expires, AWS charges the instance as an On-Demand Instance. You can repurchase the Reserved Instance to continue to use the discounted rate. You can also schedule a Reserved Instance to automatically renew.

Cancel or modify a Reserved Instance

You can't cancel a Reserved Instance. After purchase, you're committed for the full term. However, you can modify the Reserved Instance. For information about the types of available modifications, see Modify Reserved Instances.

If you longer need a Reserved Instance that you purchased, then you can sell the Reserved Instance on the Amazon EC2 Reserved Instance Marketplace. You must have access to a US bank account to use the Reserved Instance Marketplace.

Related information

Amazon EC2 billing and purchasing options

Should I use Savings Plans or Reserved Instances for my EC2 instance?