What is an Amazon EC2 Reserved Instance?

Last updated: 2022-06-08

What is an Amazon Elastic Compute Cloud (Amazon EC2) Reserved Instance, and what benefits does it provide?

Resolution

An Amazon Reserved Instance (RI) is a billing discount that allows you to save on your Amazon EC2 usage costs. When you purchase a Reserved Instance, you can set attributes such as instance type, platform, tenancy, Region, or Availability Zone (optional).

Any existing or new On-Demand Instances matching the selected attributes are charged at the discounted Reserved Instance price. Reserved Instances act as an automatic discount on new or existing On-Demand Instances in your account.

Note: Because a Reserved Instance is a billing discount, it doesn't affect the running of any existing instances.

Receiving RI discounts

The Reserved Instance doesn't provide a discount until you launch an instance with the required specifications.

You receive discounts or capacity reservations depending on the RI that you choose:

  • Regional Reserved Instances provide a pricing discount that helps you save money. Regional RIs apply a discount to On-Demand Instances you run in a particular Region.
  • Zonal Reserved Instances allow you to create a capacity reservation for an instance type within a specific Availability Zone. Zonal RIs also provide substantial discounts over On-Demand Pricing.

For more information on the differences between zonal and Regional Reserved Instances, see Regional and zonal Reserved Instances (scope).

Size of RI discounts

The size of the discount that you receive depends on whether you're using a standard RI or a convertible RI:

  • Standard RIs provide the largest discount for a specific instance type over a long-term contract.
  • Convertible RIs provide a smaller discount, but let you change the instance type during the contract.

For more information on Standard and Convertible Reserved Instances, see Types of Reserved Instances (offering classes).

Purchasing an RI

If you are considering purchasing a RI, see What should I consider before purchasing an Amazon EC2 Reserved Instance?


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