Amazon EC2 Charges
From Amazon Elastic Compute Cloud: 2008-08-08
With Amazon EC2, you don’t have to pay upfront fees, you don’t have to commit to a fixed amount of bandwidth, and you don’t have to meet any minimum usage requirements. As with other AWS services, you only pay for what you use.
The following figure summarizes how you are charged for using Amazon EC2.
For detailed information on Amazon EC2 charges, go to the Amazon EC2 Portal Page.