Reserved Instances FAQs
What is a Reserved Instance?
Reserved Instances give you the option to make a low, one-time payment for each instance you want to reserve and in turn receive a significant discount on the hourly usage charge for that instance. After the one-time payment for an instance, that instance is reserved for you, and you have no further obligation; you may choose to run that instance for the discounted usage rate for the duration of your term, or if and when you do not use the instance, you will not pay usage charges on it.
How is a Reserved Instance different than an On-Demand Instance?
Functionally, Reserved Instances and On-Demand instance are the same. They are launched and terminated in the same way, and they function identically once running. This makes it easy for you to seamlessly use both Reserved and On-Demand Instances without making any changes to your code. The only difference is that with a Reserved Instance, you pay a low, one-time payment and receive a lower usage rate to run the instance than with an On-Demand Instance.
How do I purchase and start up a Reserved Instance?
You purchase an EC2 Reserved Instance by calling the PurchaseReservedInstancesOffering API method. Launching a Reserved Instance is no different than launching an On-Demand Instance. You simply use the RunInstances command or launch an instance via the AWS Management Console.Amazon EC2 will optimally apply the cheapest rate that you are eligible for in the background.
How do I control which instances are billed at the Reserved Instance rate?
The RunInstances command does not distinguish between On-Demand and Reserved Instances. When computing your bill, our system will automatically optimize which instances are charged at the lower Reserved Instance rate to ensure you always pay the lowest amount.
How many Reserved Instances can I purchase?
You can purchase up to 20 Reserved Instances per Availability Zone each month with the EC2 APIs. If you need additional Reserved Instances, complete the Registration Form.
Can a Reserved Instance that I’ve bought for a particular instance type (i.e. High-CPU Extra Large Instance) be applied to a different instance type that I am running (i.e. Standard Large Instance)?
No. Each Reserved Instance is associated with a specific instance type, and can only be applied to that instance type for the duration of the Reserved Instance term.
Can I move a Reserved Instance from one Region or Availability Zone to another?
No. Each Reserved Instance is associated with a specific Region and Availability Zone, which is fixed for the lifetime of the Reserved Instance and cannot be changed.
Do I need to specify an Availability Zone when I launch my instances in order to take advantage of my Reserved Instances?
Yes. When you purchase a Reserved Instance you specify the Availability Zone in which you want to reserve that instance. In order to use that Reserved Instance, you need to ensure that you launch your instance in that same Availability Zone. Additionally, you can purchase a Reserved Instance in an Availability Zone where you already have a running instance, and the Reserved Instance will automatically get applied to that existing instance.
Can I cancel a Reserved Instance?
The one-time payment for a Reserved Instances is not refundable. However, you can choose not to run or entirely stop using your Reserved Instance at any time, at which point you will not incur any further usage charges.
What happens when my Reserved Instances term comes to an end?
Any instances that you have that are still running will continue to run, but will be charged at the standard On-Demand hourly rate.
When are Reserved Instances activated?
A Reserved Instance is activated once your one-time payment has successfully been authorized. You can follow the status of your Reserved Instance on the AWS Account Activity page.