No. It only performs subnet math in your browser. No host, port or external IP is contacted.
Subnet Calculator
IPv4, CIDR, mask, broadcast, hosts and basic VLSM in your browser.
Fast subnetting with no external service.
The calculator turns an IP and CIDR prefix into network, broadcast, mask, wildcard, usable range and host count. The VLSM area accepts simple name:hosts lines and allocates non-overlapping blocks inside the base network.
IP, prefix and instant result.
- Enter an IPv4 address and adjust the CIDR prefix slider.
- Check network, broadcast, mask, wildcard and usable hosts.
- Optionally enter name:hosts lines to generate basic VLSM subnets.