ECU – The EC2 Compute Unit provides the relative measure of the integer processing power of an Amazon EC2 instance. In order to make it easy for developers to compare CPU capacity between different instance classes, we have defined an Amazon EC2 Compute Unit. The amount of CPU that is allocated to a particular instance is expressed in terms of these EC2 Compute Units. One ECU currently provides CPU capacity equivalent to a 1.0-1.2 GHz 2007 Opteron or 2007 Xeon processor.