Subnet Abacus
Subnet Abacus is an interactive, visual IPv4 Subnet Calculator. It is designed to show the mathematical relationships between the various network attributes and to update them dynamically as changes are made. In the "Base IP" field, you can specify an IP address (10.0.0.0), an IP address/CIDR combination (10.0.0.0/24), or an IP address/Subnet mask (10.0.0.0 255.255.255.0). Once the base IP address is parsed, the subnet mask can be adjusted using the slider and drop-down elements. The lower section of the application is used to divide the upper subnet into smaller subnets.
If a network type other than "Classless" is selected your options will be limited appropriately. Classful networks are largely a relic of the past, you probably want to stick to the "Classless" option.
The buttons at the bottom will pop up a separate window or windows containing the requested information. Pay attention to the number of subnets or hosts being generated - large numbers make take a long time or crash. The subnet charts generated are compatible with cut and paste into Microsoft Excel.
Screenshots:
Version 0.1, animated to show function:
New version (0.2):
Download:
Subnet Abacus.exe (v2) Updated Dec 20 2025SubnetAbacus.exe (v1) Last Updated ~2015