This is a simple IP calculator.
Enter the IP address and mask bits ( use the slider or enter the bits in the corresponding field) and it will show you basic information about the host address and subnetwork: Subnetwork Address, Subnetwork Mask in decimal format, Broadcast address and the Wildcard Mask used in access control lists.
Use the arrows to go to the previous or next adjacent subnetworks. This is useful when setting up many consecutive networks with non obvious mask lenghts like /27 .