The Application Load Balancer billing is based on Load Balancer Capacity Unit (LCU) metrics. The new CloudWatch metrics for Classic Load Balancer namely, EstimatedProcessedBytes, EstimatedALBActiveConnectionCount, and EstimatedALBNewConnectionCount give you visibility into traffic profile in each of the dimensions that constitute an LCU. The fourth metric, EstimatedALBConsumedLCUs gives you the estimated LCU count that your traffic will be billed if you use an Application Load Balancer. The four metrics are approximations and the sole purpose of these metrics is to give you an estimate of your bill if you were to transition from Classic to the Application Load Balancer.